e Ecology Organizer (Topic 5 and Option G) VocabularyTerm Definition Examples

Species

Habitat

Population

Community

Ecosystem

Ecology

AutotrophSynonym:

HeterotrophSynonym:

Food Chain

Food Web

Decomposer

Detritivore

Saprotroph

Trophic Level

Greenhouse Effect

Global Warming

Climate Change

Precautionary Principle

Natality

Mortality

Emigration

Immigration

Biotic Factors

Abiotic Factors

pH

Enzyme

Breeding

Territory

Quadrat

Transect

NicheNiche:

Fundamental Niche:

Realized Niche:

Competition

Competitive Exclusion

Herbivory

Predation

Parasitism

Host

Exoparasites

Endoparasites

Mutualism

Biomass

Primary ProductionProduction:

Gross Production:

Net Production:

SuccessionSuccession:

Primary Succession:

Secondary Succession:

Climax Community

Biosphere

Biome

Biodiversity

InvasiveInvasive Species:

Deliberate Introduction:

Accidental Introduction:

Biological Control

Biomagnification

Ozone Layer

Indicator Species

Extinction

Nature Reserve

Edge Effects

Wildlife Corridors

Restoration

ConservationConservation:

In Situ Conservation:

Ex Situ Conservation:

Captive Breeding

Botanic Garden

Seed Bank

Landrace

r-Strategy

K-Strategies

Maximum Sustainable Yield

Carrying Capacity

5.1.1 Define species, habitat, population, community, ecosystem and ecology.

Place the terms population, community and ecosystem into the individual circles to express their relationship. Explain how you chose to place them.

The term species is defined as a potentially interbreeding population having a common gene pool and producing fertile young. Outline why this definition cannot be applied to all living organisms.............................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................

(Total 4 marks)

Use the terms population, community and ecosystem to describe all components of this picture.

Apply one or more of the terms that follow to describe each of the listed features of a freshwater lake: population, ecosystem, habitat, abiotic factor, community and biomass.

The whole lake All the frogs of the lake The flow of water through the lake All the plants and animals present The total mass of vegetation growing in the lake The mud of the lake The temperature variations in the lake

Population Species

What term refers to a community and its abiotic environment?A. BiosphereB. EcosystemC. HabitatD. Niche

In communities, groups of populations live together and interact with each other. Outline the importance of plants to populations of other organisms in a community.

(Total 6 marks)

Ecology

Population Community

Ecosystem

Habitat

5.1.2 Distinguish between autotroph and heterotroph.

Energy Source Trophic Level Synonym Organic Molecule Origin? Example

Autotroph

Heterotroph

Outline why the transparency of water is important to organisms living in an aquatic habitat..........................................................................................................................................................................................................................................................................................................................................................................................................

5.1.3 Distinguish between consumers, detritivores and saprotrophs.

Shark vs. Mold Crab vs. Shark Mold vs. Crab

Similarities

Differences

Which organisms externally digest dead organic matter and then absorb the nutrients?A. Autotrophs

B. DetritivoresC. HeterotrophsD. Saprotrophs

5.1.4 Describe what is meant by a food chain, giving three examples, each with at least three linkages (four organisms). Note: Each food chain should include a producer and consumers, but not decomposers. Named organisms at either species or genus level should be used. Common species names can be used instead of binomial names. General names such as “tree” or “fish” should not be used.

Palm roots Mouse Lizard Sun Bear

Give one example of a marine food chain (min. 4 organisms)

Give one example of a terrestrial food chain (min. 4 organisms)

Give one other example of a food chain (min. 4 organisms)

What do the arrows represent in a food chain?

5.1.5 Describe what is meant by a food web.

How are these food web examples organized? Explain.

5.1.6 Define trophic level.

Label: Primary consumers, Carnivores, Producers, Apex Predators, Herbivores, Tertiary Consumers, Secondary Consumers.Highlight: Heterotrophs (yellow), Autotrophs (green)Outline: Carnivores of carnivores (red), carnivores of herbivores (orange), Apex Predators (brown)

5.1.7 Deduce the trophic level of organisms in a food chain and a food web.

Identify the trophic level for each of the organisms in the food web you created on the previous page.

The diagram below is a simplified version of a food web from Chesapeake Bay. The arrows indicate the direction of energy flow and the numbers indicate species within the food web.

At which trophic level or levels does species II function?A. 2nd and 3rd consumerB. 3rd consumerC. 3rd and 4th consumerD. Producer

Which of the species feed both as secondary consumers and as tertiary consumers?A. I, II and IV onlyB. I, III and V onlyC. I, IV and V onlyD. III, IV and V only

5.1.8 Construct a food web containing up to 10 organisms, using appropriate information.

Activity: Place the following organisms into a food web below:

a) Anchoviesb) Herringc) Rockfishd) Squide) Dolphinf) Pufferg) Phytoplanktonh) Salmoni) Octopusj) Porpoisek) Tunal) Sharkm) Sea Lionn) Sealo) Sardinesp) Lancetq) Mackerelr) Jellyfishs) Barnaclest) Shrimpu) Hakev) Krillw) Zooplankton

5.1.9 State that light is the initial energy source for almost all communities.

Explain how all of the energy transferred in the food chains of 5.1.4 originates from the Sun.

5.1.10 Explain the energy flow in a food chain.5.11 State that energy transformations are never 100% efficient.

The arrow shows a flow of energy.An arrow diverging from the pathway represents lost energyThe width of the arrow represents the proportion of energy remaining or lost.

List the three ways energy is lost when moving from one trophic level to the next.1)2)3)

Show the Sankey diagram for energy transformations on pg. 103 of Walpole and explain it.

Show the linear food chain diagram involving energy flow on pg. 144 of Clegg and explain it.

The energy flow diagram below for a temperate ecosystem has been divided into two parts. One part shows autotrophic use

of energy and the other shows the heterotrophic use of energy. All values are kJm–2

yr–1

.

gro sspro du ctio n

4 3 51 0feed in g14 6 9 0

ph o to syn th esis

he a t2 3 93 0

h e at 1 4 1 4 0

n e t p ro du ctio nX

sto rag e4 9 00

s to rag e5 4 0

au to tro ph icre sp ira tion

h e te ro trop h icresp ira tio n

A u to tro p h s H ete ro tro p h s

(a) Calculate the net production of the autotrophs...........................................................................................................................................................................................................................................................................

(1)(b) (i) Compare the percentage of heat lost through respiration by the autotrophs with the heterotrophs.

...........................................................................................................................

...........................................................................................................................(1)

(ii) Most of the heterotrophs are animals. Suggest one reason for the difference in heat losses between the autotrophs and animal heterotrophs.......................................................................................................................................................................................................................................................

(1)The heterotrophic community can be divided into food webs based upon decomposers and food webs based upon herbivores. It has been shown that of the energy consumed by the heterotrophs, 99% is consumed by the decomposer food webs. (c) State the importance of decomposers in an ecosystem.

.....................................................................................................................................

..................................................................................................................................... (1)(d) Deduce the long-term effects of sustained pollution which kills decomposers on autotrophic productivity.

.....................................................................................................................................

..................................................................................................................................... (2) (Total 6 marks)

5.1.12 Explain reasons for the shape of pyramids of energy.

Draw the 2 pyramids of energy on pg. 104 of Walpole and explain each.

Draw the 2 pyramids of energy on pg. 42 of the Allott study guide and explain each.

Draw the 4 pyramids of energy on pg. 145-146 of Clegg and explain each.

Draw the pyramid of energy on pg. 170 of Allott and explain it.

The total solar energy received by a grassland is 5 × l05

kJ m–2

y–1

. The net production of the grassland is 5 × 102

kJ m–2

y–1

and its gross production is 6 × l02

kJ m–2

y–1

. The total energy passed on to primary consumers is 60 kJ m–2

y–1

. Only 10% of this energy is passed on to the secondary consumers.(a) Calculate the energy lost by plant respiration.

.....................................................................................................................................

..................................................................................................................................... (2)(b) Construct a pyramid of energy for this grassland.

(3) (Total 5 marks)

The diagram below represents an energy pyramid and four trophic levels.

IV

III

II

I1 00 00 0 k J m y r– 2 – 1

[Source: adapted from www.bio.miami.edu/dana/160/pyramid.gif](i) Identify the trophic level of the organisms indicated below.

I. ...............................................................................................................IV. ...............................................................................................................

(2)

(ii) Calculate the approximate amount of energy in kilojoules transferred in m–2

yr–1

from trophic level I to trophic level II...................................................................................................................... kJ

The diagram below represents a pyramid of energy for a community of organisms. State what the bars labelled I and II indicate.

Tro p h iclev e l

E n e rg y flo w / k Jm y

I

II

– 2 – 1

I. .........................................................................................................................II. .........................................................................................................................

5.1.13 Explain that energy enters and leaves ecosystems, but nutrients must be recycled.

5.1.14 State that saprotrophic bacteria and fungi (decomposers) recycle nutrients.

Show the food chain as a pyramid of biomass involving energy flow on pg. 144 of Clegg and explain it.

5.2.1 Draw and label a diagram of the carbon cycle to show the processes involved.

Copy the diagram from pg. 106 of Walpole.

CO2 Sources Processes that add CO2 CO2 Sinks Processes that remove CO2

The diagram below shows a simplified version of the carbon cycle. 2

III

C O in a tm o sp h e re

P rim aryC o n su m er

S eco n d a ryC o n su m er

F u e ls P lan ts

What processes are involved in the transfer of carbon at stages I and II?I II

A. combustion photosynthesisB. photosynthesis respirationC. combustion respirationD. fossilization respiration

Outline ways in which leaves take part in the carbon cycle in ecosystems, apart from photosynthesis.(Total 4 marks)

The diagram below is part of a carbon cycle diagram for an ecosystem in a pond.

(a) State the names of the processes that(i) convert carbon dioxide into organic compounds in pond weeds and algae

..........................................................................................................................(1)

(ii) convert organic compounds in pond weeds, algae and primary consumers into carbon dioxide...........................................................................................................................

(1) (b) (i) Draw arrows on the diagram above to show how the saprotrophs obtain carbon.

(1) (ii) Explain the role of saprotrophs in recycling carbon.

..........................................................................................................................

.......................................................................................................................... (2)

(c) Draw a box on the diagram in an appropriate position, labelled organic compounds in secondary consumers. Draw arrows to show the links between secondary consumers and other parts of the carbon cycle.

(2) There has been a significant increase in the concentration of carbon dioxide in the Earth’s atmosphere during the last fifty years.

(d) (i) Suggest two reasons for this increase in atmospheric carbon dioxide concentration.1. ................................................................................................................

................................................................................................................2. ................................................................................................................

................................................................................................................(2)

(ii) Suggest one effect of an increase in carbon dioxide concentration on organisms in a pond. Include in your answer the reason for the effect and the type of organisms that are affected...............................................................................................................................................................................................................................................................................................................................................................................

(2) (Total 11 marks)

5.2.2 Analyze the changes in concentration of atmospheric carbon dioxide using historical records. Note: Data from the Mauna Loa, Hawaii, or Cape Grim, Tasmania, monitoring stations may be used.

Create a simplified version of ice core graph from pg. 149 of Clegg. Explain it in your own words.

5.2.3 Explain the relationship between rises in concentrations of atmospheric carbon dioxide, methane and oxides of nitrogen and the enhanced greenhouse effect. Note: Students should be aware that the greenhouse effect is a natural phenomenon. Reference should be made to transmission of incoming shorter-wave radiation and re-radiated longer-wave radiation. Knowledge that other gases, including methane and oxides of nitrogen, are greenhouse gases is expected.

CAUSE EFFECT

Fossil Fuel Use

Increased Greenhouse Gas Concentration

Re-radiation

Natural Causes of CO2 Rise

Artificial Causes of CO2 Rise

What is a factor that increases the greenhouse effect and what is a consequence of it?Factor contributing to increases in the

greenhouse effectConsequence of the increased

greenhouse effectA. Increasing global temperatures Rising sea levelsB. Rising sea levels Increasing global temperaturesC. Increasing global temperatures Burning fossil fuels to run air conditioningD. Increases in air travel Increasing global temperatures

The graph below shows the variation in the concentration of atmospheric carbon dioxide since 1970.3 7 5

3 7 0

3 6 5

3 6 0

3 5 5

3 5 0

3 4 5

3 4 0

3 3 5

3 3 0

3 2 5

3 2 0

1970

1975

1980

1985

1990

1995

2000

C Oco n cen tra tio n

/ p p m

2

The annual fluctuation is mainly the result of changes in the levels of photosynthesis associated with the seasons in Northern Hemisphere forests. (a) (i) Describe the overall trend shown in the graph.

........................................................................................................................... (1)

(ii) Suggest a cause for the overall trend throughout the period 1970–1999............................................................................................................................ (1)

(b) (i) Using a clear label, identify any one point on the graph which shows the CO2 level in mid-summer. (1)(ii) Explain why the concentration of CO2 varies with the seasons.

...........................................................................................................................

........................................................................................................................... (2)(c) Identify one gas, other than CO2 , which is contributing to the enhanced greenhouse effect.

.....................................................................................................................................(1) (Total 6 marks)

5.2.4 Outline the precautionary principle. Note: The precautionary principle holds that, if the effects of a human-induced change would be very large, perhaps catastrophic, those responsible for the change must prove that it will not do harm before proceeding. This is the reverse of the normal situation, where those who are concerned about the change would have to prove that it will do harm in order to prevent such changes going ahead. TOK: Parallels could be drawn here between success in deterring crime by increasing the severity of the punishment or by increasing the chance of detection. If the possible consequences of rapid global warming are devastating enough, preventive measures are justified even if it is far from certain that rapid global warming will result from current human activities.

Consequences of Inaction Potential Action To Be Taken

1. 1.

2. 2.

3. 3.

4. 4.

5. 5.

6. 6.

Use pg. 151 of Clegg for guidance.

According to the precautionary principle, what should happen if there are fears that eating a food might cause a health problem?A. People should be warned about the possible health problem.B. The company producing the food should be warned about the possible health problem.C. People who have fears about the food should test it to see if it causes a real health problem.D. The company producing the food should test the food to prove that it does not cause a health problem.

5.2.5 Evaluate the precautionary principle as a justification for strong action in response to the threats posed by the enhanced greenhouse effect. Aim 8: Consider whether the economic harm of measures taken now to limit global warming could be balanced against the potentially much greater harm for future generations of taking no action now. There are also ethical questions about whether the health and wealth of future human generations should be jeopardized, and whether it is right to knowingly damage the habitat of, and possibly drive to extinction, species other than humans. The environmental angle here is that the issue of global warming is, by definition, a genuinely global one in terms of causes, consequences and remedies. Only through international cooperation will a solution be found. There is an inequality between those in the world who are contributing most to the problem and those who will be most harmed.

FACTORSEconomic Ethical Environmental

Action Taken

Action Not Taken

Use pg. 109-110 of Walpole as a guide for your arguments.

5.2.6 Outline the consequences of a global temperature rise on arctic ecosystems. Note: Effects include increased rates of decomposition of detritus previously trapped in permafrost, expansion of the range of habitats available to temperate species, loss of ice habitat, changes in distribution of prey species affecting higher trophic levels, and increased success of pest species, including pathogens.

Utilize information on pg. 45 of the Allott student study guide and pg. 153 of Clegg.

5.3.1 Outline how population size is affected by natality, immigration, mortality and emigration. Aim 7: Simulation exercises can be performed.

Create an equation:

Population Change = (_____________ + _____________) – (_____________ + _____________)

If natality is slightly larger than mortality, and immigration is much larger than emigration, what will happen to the size of a population?A. It will increaseB. It will decreaseC. It will fluctuate up and downD. It will remain constant

In the graph below, what could be causing the population change in the region II III?

A. Natality > mortality, immigration = emigrationB. Natality > mortality, immigration > emigrationC. Natality > mortality, immigration < emigrationD. Natality = mortality, immigration < emigration

Which factors can cause a decrease in a population?Emigration Natality Immigration Mortality

A. Low High Low HighB. High Low High LowC. High Low Low HighD. Low High High Low

Explain the reasons for the sizes of animal populations within communities changing and the reasons for them remaining constant.

(Total 8 marks)

Global Warming

5.3.2 Draw and label a graph showing a sigmoid (S-shaped) population growth curve.

Draw the shape of the S-curve, label the exponential, transitional and plateau phases and explain what is occurring in each (Walpole pg. 112).

How would this graph look different or be explain differently with regards to microbial populations (Clegg pg. 155)?

5.3.3 Explain the reasons for the exponential growth phase, the plateau phase and the transitional phase between these two phases.

5.3.4 List three factors that set limits to population increase.

Density-Independent Factors

……………………………………………………………………………………………………………………………………………………………………………………………………………………………….

Density-Dependent Factors

G.1.1 Outline the factors that affect the distribution of plant species, including temperature, water, light, soil pH, salinity and mineral nutrients.

Effect of abiotic factors (high or low) on plant growth and distributionTemperature Water Light pH Salinity Minerals

Exponential Phase

Transitional Phase

Plateau Phase

Promote Growth

Limit Growth

Population Size

High

Low

Plants native to warm climates sometimes suffer injuries when exposed to relatively low temperatures. For example, temperatures in the range of 10 ⁰C to 15 ⁰C can cause “chilling injuries” to some sub-tropical plants that normally grow between 20 ⁰C and 25 ⁰C. These “chilling injuries” may affect gene expression and reduce the rates of photosynthesis and protein synthesis. Some plants are more resistant to “chilling injuries” than others.These injuries could be due to damaged membranes. Membrane lipids consist of a mixture of saturated fatty acids (no double bonds) and unsaturated fatty acids (one or more double bonds). Saturated fatty acids have a higher melting point than unsaturated fatty acids.The table below shows the main fatty acid composition (as a percentage of the total fatty acid content) of mitochondrial membranes in various plants and the ratio of unsaturated/saturated fatty acids.

Fatty acid composition / %Chill-resistant plants Chill-sensitive plants

Fatty acid Number ofdouble bonds

Cauliflower Turnip Pea Bean Sweetpotato

Maize

Palmitic 0 21.3 19.0 12.8 24.0 24.9 28.3Stearic 0 1.9 1.1 2.9 2.2 2.6 1.6Oleic 1 7.0 12.2 3.1 3.8 0.6 4.6

Linoleic 2 16.4 20.6 61.9 43.6 50.8 54.6Linolenic 3 49.4 44.9 13.2 24.3 10.6 6.8

Ratio of unsaturated tosaturated fatty acids

3.2 : 1 3.9 : 1 3.8 : 1 2.8 : 1 1.7 : 1 2.1 : 1

(a) Identify,(i) the plant with the lowest ratio of unsaturated fatty acids to saturated fatty acids;

..........................................................................................................................(1)

(ii) which saturated fatty acid has the highest percentage composition...........................................................................................................................

(1) (b) Deduce which data in the table determines whether a plant is either chill-resistant or chill-sensitive.

....................................................................................................................................

....................................................................................................................................(2)

(c) Suggest which physical property of mitochondrial membranes allows some plants to be chill-resistant.....................................................................................................................................

(1) (d) Predict how the function of the mitochondria will be affected when chill-sensitive plants are cooled.

.................................................................................................................................... (1)

Researchers have carried out long-term studies into the relationship between the exposure of plants to elevated levels of CO2 concentration and their tolerance to freezing. The chart below shows the amount of membrane damage caused when plants are grown at different temperatures in normal or elevated levels of CO2 concentration. The membrane damage was indicated by the amount of membrane leakage and this was measured in terms of relative conductivity (high conductivity indicates membrane leakage).

R ela tiveco n du ctiv ity

1 .0

0 .8

0 .6

0 .4

0 .2

0 .0

K ey : no rm a l le ve ls o f C O 2 co n cen tra tio n e le va ted lev e ls o f C O 2 co nc en tra tio n

S ign ifca n t d am ag e

C on tro l a t 0 .0 –4 .0 –6 .5 –9 .0 2 0 C

C h ill trea tm e n t / C(e) Identify the relationship between chill treatment and membrane leakage at normal levels of CO2 concentration.

.................................................................................................................................... (1)

(f) Identify the temperature at which significant membrane damage begins to occur in plants treated with elevated levels of CO2 concentration.....................................................................................................................................

(1) (g) Evaluate the effect of elevated levels of CO2 concentration on the freezing tolerance of plants.

.................................................................................................................................... (1)

Researchers wanted to evaluate the effect of chilling treatment on the rate of photosynthesis, measured by CO2 uptake. This was carried out at normal levels and elevated levels of CO2 concentration. The photosynthetic rate was measured three weeks after chilling treatment began.

(h) Calculate the change in CO2 uptake from 0.0 ⁰C to – 4.0 ⁰C in plants grown in elevated levels of CO2 concentration.........................................................................................................................................................................................................................................................................

(1)(i) Outline the effect of chilling treatment on rate of photosynthesis of plants grown at different levels of CO2

concentration.........................................................................................................................................................................................................................................................................

(2) (j) Suggest what factor other than membrane damage causes a drop in the rate of photosynthesis as the temperature

decreases.....................................................................................................................................

(1) (k) Analyse the long-term consequences of the greenhouse effect on the freezing tolerance and chilling tolerance of

plants.........................................................................................................................................................................................................................................................................

(2) (Total 15 marks)To test how temperature affects growth, some plants were grown at 20°C and another group at 30 ⁰C. After a number of weeks, the heights of the plants were measured. Explain how the t-test could be used to test the significance of the effect of temperature on plant growth.

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (3)

A study was conducted to investigate the growth factors affecting plants in urban areas compared to rural areas. Fast-growing clones of Eastern cottonwood trees (Populus deltoids) were grown in both urban and rural sites. The results of three successive growing seasons (X, Y, and Z) are shown below.

1 0 0

8 0

6 0

4 0

2 0

0

2 0

4 0

1 0 0

8 0

6 0

4 0

2 0

0

2 0

4 0

1 0 0

8 0

6 0

4 0

2 0

0

2 0

4 0

R o o tb io m a ss / g

S h o o tb io m a ss / g

S ea so n X S ea so n Y S ea so n Z

L I H V N Y L I H V N Y L I H V N Y

K e y: L I an d H V a re ru ra l s i te s an d N Y is an u rb an s ite(a) Identify the site which most favours the growth of cottonwood trees.

.....................................................................................................................................(1)

(b) Calculate the ratio of shoot biomass to root biomass in site LI during season X......................................................................................................................................

(1) (c) Analyse the data for growth patterns over the three years of the study.

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (3)

A further study showed that differences in light, temperature, water, CO2 concentration, and the soil could not account for the differences in growth of the cottonwoods in the urban and rural areas. (d) Suggest a reason which could account for the growth differences.

.....................................................................................................................................(1) (Total 6 marks)

G.1.2 Explain the factors that affect the distribution of animal species, including temperature, water, breeding sites, food supply and territory.

Effect of abiotic/biotic factors (high or low) on plant growth and distributionTemperature Water Breeding Sites Food Supply Territory Competition

High

Low

The relationship between the numbers of rodent species and rainfall was studied in dry areas of Chile and in the south-west of the United States. The results of the study are shown in the scattergraph below.

K e y :C h ileU S A

8

6

4

2

0

N u m b e r o f sp e c ie s

1 0 5 0 1 00 5 0 0

R a in fa ll / m m

(a) Calculate the difference between the number of species found at 80 mm of rainfall and at 100 mm of rainfall in(i) Chile.

........................................................................................................................... (1)

(ii) the USA............................................................................................................................

(1) (b) Compare the relationship between the number of rodent species and rainfall in Chile with that of the USA.

.....................................................................................................................................

..................................................................................................................................... (2)

(c) Suggest two reasons for the relationship between the number of rodent species and rainfall in each country................................................................................................................................................................................................................................................................................................................................................................................................................

(2) (Total 6 marks)In Australia, studies were performed on wild grassland sites containing shrubs to determine the effect that fires have on the biodiversity of birds living there. The birds occupy different habitats in the ecosystem, and each is affected differently by the fires. Counts were made of the numbers of birds of several species immediately before the fire, and then at intervals in the following years.

(a) State the time after the fire before the greatest number of ground parrots was found.....................................................................................................................................

(1) (b) The white-cheeked honeyeater eats nectar from flowering plants. Using the data, predict the effect the fire had on

these flowering plants.........................................................................................................................................................................................................................................................................

(2) (c) Immediately before the fire (0 years), the Simpson diversity index for 10 hectares of the ecosystem was 5.4. Predict,

giving a reason, whether you would expect this value to increase, decrease or remain unchanged 10.5 years after the fire.........................................................................................................................................................................................................................................................................

(2) (d) Suggest two reasons why the results varied for the different bird species.

1. ....................................................................................................................................................................................................................................................

2. ....................................................................................................................................................................................................................................................

(2) (Total 7 marks)

Sea water temperature has an effect on the spawning (release of eggs) of echinoderms living in Antarctic waters. Echinoderm larvae feed on phytoplankton. In this investigation, the spawning of echinoderms and its effect on phytoplankton was studied.

In the figure below, the top line indicates the number of larvae caught (per 5000 litres of sea water). The shaded bars below show when spawning occurred in echinoderms.

= 0 % to 2 5 %= 2 5 % to 7 5 %= 7 5 % to 1 0 0 %

The concentration of chlorophyll gives an indication of the concentration of phytoplankton. Note: that the seasons in the Antarctic are reversed from those in the northern hemisphere.

D ec D ec D ecM ar M arJu n Ju nS ep S ep

800

1 00

10

1

0 .1

0 .0 1

210–1–2

Sea t

empe

ratu

re /°

C

N um ber o fech inod erm la rv ae

% S p aw nin g o fech inod erm

S ea tem pera tu re / °C

L o g C h lo ro p hy llcon cen trat io n

/ m g m –3

10

19 93 19 94

phy to p lank to n

(a) State the trophic level of echinoderm larvae......................................................................................................................................

(1) (b) Identify the period during which the spawning of echinoderm lies between 25% and 75%.

.....................................................................................................................................(1)

(c) Explain the relationship between the seasons and the concentration of phytoplankton...........................................................................................................................................................................................................................................................................

(2) (d) (i) Outline the effect of sea water temperature on echinoderm larvae numbers.

...........................................................................................................................

...........................................................................................................................(2)

(ii) Using the data in the figure, predict the effect of global warming on echinoderm larvae numbers.......................................................................................................................................................................................................................................................

(2) (Total 8 marks)In Norway the body masses of young moose (calves) fluctuate from year-to-year in the fall (autumn). Because of the regularity of the pattern, the fluctuation was thought to be related to food availability. Moose (Alce alce) eat bilberry (Vaccinium myrtillus), as do the bank vole (Clethrionomys glareolus). It was known that the bank vole populations peaked the year after high bilberry production.These population changes were studied in a Northern area and a Southern area of Norway. The variation in mean fall (autumn) body mass of moose calves and the bank vole density are shown for the two areas in the graphs below.

(a) (i) State the lowest body mass of moose calves in the Northern area............................................................................................................................

(1) (ii) Determine the year in which bank vole density was highest in the Northern area.

...........................................................................................................................(1)

(b) Compare the variations in the moose calf body mass in both areas...........................................................................................................................................................................................................................................................................

(2) (c) Evaluate the hypothesis that both populations vary according to the availability of the common food source, the

bilberry...........................................................................................................................................................................................................................................................................

(2) (Total 6 marks)Sea turtles have existed on Earth for millions of years, but are now threatened by human activities, both at sea and on the sandy beaches where they lay their eggs. All species of sea turtle reproduce in a similar way. During the breeding season, when females have mated at sea they emerge from the ocean at night and drag themselves up a beach. They dig a pit into which they lay fertilized eggs. After covering the eggs with sand the females return to the ocean. The warmth of the sun on the sand incubates the eggs allowing the development of young turtles, called hatchlings. These emerge after about 50 days and move down the beach at night to the ocean.

Ecologists have been keeping records of the nesting activity of sea turtles along the eastern coastline of Florida since the 1950s. The bar chart below shows the mean number of nests per kilometre of beach between 1989 and 1998 for the three species of sea turtle that are commonly found.

3 0

2 8

2 6

L atitu d e / d eg reesn o rth o f th e eq u a to r

L o g g e rh ead s( )C a re tta caret ta

G re en T u rtle s( )C helo n ia m y d as

L ea th erb ack s( )D erm o ch e lys coria cea

0 0 01 0 0 0 5 0 5

N e sts k m – 1

C an a v e ra l

M elb o u rn e B ea ch

H u tch in so n Is la n dJu p ite r Is lan d

Ju n o B e ach

B o c a R a to n

(a) State which species of turtle nests in the greatest numbers on Jupiter Island......................................................................................................................................

(1)(b) Compare the distribution of nesting in the three species of turtle along the eastern coastline of Florida.

.....................................................................................................................................

..................................................................................................................................... (2)

(c) The parts of the coastline where there was most nesting were those where there was least human activity and therefore least artificial light. Suggest an experiment that could be done to test whether artificial light discourages nesting................................................................................................................................................................................................................................................................................................................................................................................................................

(2)A study was undertaken at the southernmost nesting site, at Boca Raton. Here a beach lies adjacent to a series of apartment buildings that are unoccupied during the nesting season. These buildings therefore shade the beach from artificial light further inland. The location of nest sites along the beach has been accurately recorded, in relation to the position of the apartment buildings. The chart below shows the locations of the nests and apartment buildings and the height of the buildings as seen from the beach.

Villa D elM a r

30 00 S ou th W hiteh a ll S o u th S tra tfo rd A rm sA rv ita

W hiteh a llP lacide

1 0 0 m etres

H eig h t / m

L o ca tio n o f n ests ( )an d

ap a rtm en t b u ild in gs ( )

6 04 02 0

0

A tlan tic O ce an

(d) Explain how the distribution of turtle nests provides evidence for female turtles choosing sites that are dark at night..........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................

(4) On beaches where there is no human activity, hatchlings move directly towards the ocean after emergence at night. The

hatchlings can orientate themselves using one or more external stimuli. An experiment was done at Boca Raton to test the ability of hatchlings to locate the ocean at different levels of artificial light. Four sites were chosen and numbered 1–4, ranging from the darkest site (1), to the site most exposed to artificial lighting (4). At each site a four-metre diameter circle was marked. Hatchlings were released at the centre of each circle and the trails made in the sand by their movements were recorded. The diagrams below show these trails. The arrow head on the outside of the circle shows the mean direction of the tracks.

(e) Compare the movement of the hatchlings at the different intensities of artificial light.

.....................................................................................................................................

.....................................................................................................................................(2)

(f) Deduce one external stimulus, and the source of this stimulus, that allows hatchlings to orientate themselves at sites unaffected by human activity.......................................................................................................................................

(1) (g) Using the data in this question,

(i) explain two reasons for artificial light reducing the chances of survival of sea turtles..................................................................................................................................................................................................................................................................................................................................................................................

(2) (ii) suggest one conservation measure, aimed at increasing the chances of survival of sea turtles.

...........................................................................................................................

...........................................................................................................................(1) (Total 15 marks)

The reticulated python (Python reticulatus), a species of snake, consumes rats as part of its diet. The graph shows changes in the proportion of rats in the diet of male and female reticulated pythons from southern Sumatra as the length of the snake increases.

1 .0

0 .8

0 .6

0 .4

0 .2

0 .0

M a le sF em a les

1 00 2 00 3 00 4 00 5 00 6 00 7 00

L en g th o f sn a k e / cm

P ro p or tio n o f d ie tco m p o se d o f ra ts

(a) Identify the relationship between the proportion of diet composed of rats and the length of female pythons......................................................................................................................................

(1)(b) Compare the feeding preferences of female and male pythons of lengths between

(i) 100 and 300 cm;...........................................................................................................................

(1)(ii) 300 and 400 cm.

........................................................................................................................... (1)

(c) Suggest two reasons for the differences in feeding preferences of the pythons as length increases...........................................................................................................................................................................................................................................................................

(2)The snakes were bought at local markets and skinning factories in Sumatra. Therefore, the origin of the individual snakes was not known. Estimations about prey size and species were made from fur and skeletal remains in the gut of the snakes.(d) Suggest two factors that could influence the reliability of the results of this investigation.

.....................................................................................................................................

..................................................................................................................................... (2) (Total 7 marks)

G.1.3 Describe one method of random sampling, based on quadrat methods, that is used to compare the population size of two plant or two animal species.

Develop a method with drawings for the use of a quadrat from pg. 475 of Walpole and pg. 152 of Allott student study guide.

What is an advantage of estimating plant populations by random sampling using quadrats?A. Accurate estimates can be obtained more quickly than if every plant in the population is counted.B. Random samples can be taken from the most convenient parts of the habitat.C. Numbers of plants in each quadrat can be estimated quickly.D. Marking and recapture of plants is not necessary.

Outline the quadrat method of random sampling used to determine the population of a plant species.(Total 6 marks)

________________________________________________________________________________________________________________________

________________________________________________________________________________________________________________________

________________________________________________________________________________________________________________________

________________________________________________________________________________________________________________________

________________________________________________________________________________________________________________________

G.1.4 Outline the use of a transect to correlate the distribution of plant or animal species with an abiotic variable.

List the 3 steps for using a transect to take samples:

1.

2.

3.Why should we use a point transect?

Why should we use a continuous belt transect?

Describe how standard deviation is useful in comparing ecological data between two sites.(Total 4 marks)

G.1.5 Explain what is meant by the niche concept, including an organism’s spatial habitat, its feeding activities and its interactions with other species.

G.1.8 Distinguish between fundamental and realized niches. Note: The fundamental niche of a species is the potential mode of existence, given the adaptations of the species. The realized niche of a species is the actual mode of existence, which results from its adaptations and competition with other species.

G.1.6 Outline the following interactions between species, giving two examples of each: competition, herbivory, predation, parasitism and mutualism.

Interaction – Describe Terrestrial Example Marine Example

Competition

Herbivory

Predation

Parasitism

Mutualism

Explain how parasitism differs from mutualism with reference to named organisms.

Example Organism: Example Organism:Fundamental

Niche

Realized Niche

...............................................................................................................................................

...............................................................................................................................................

...............................................................................................................................................

...............................................................................................................................................

...............................................................................................................................................

...............................................................................................................................................(Total 6 marks)

G.1.7 Explain the principle of competitive exclusion.

Provide an example where three or more organisms occupythe same fundamental niche, but through the principle ofcompetitive exclusion the organisms realized niche is in factsmaller. Explain each niche and in terms of feeding, habitatand species interactions.

Explain the significance of the principle of competitive exclusion..............................................................................................................................................................................................................................................................................................................................................................................................................................................

(Total 3 marks)G.1.9 Define biomass.

G.1.10 Describe one method for the measurement of biomass of different trophic levels in an ecosystem. Aim 8: Ethical issues of returning the species and destructive techniques should be considered.

G.2.1 Define gross production, net production and biomass.

A pine forest has a net production of 42 kJ m–2

year–1

. Respiration is 100 kJ m–2

year–1

. Calculate the gross production.

....................................................................................................................................Explain why the gross production of a species in an ecosystem is always higher than the net production.

.....................................................................................................................................

.....................................................................................................................................(2)

G.2.2 Calculate values for gross production and net production using the equation: gross production – respiration = net production. 2 GP – R = NP

Photosynthesis

1. Fill in the missing values (Allott pg.330)2. Calculate autotroph net production.3. Compare percent heat loss from heterotrophs with that of autotrophs.4. Suggest a reason for the difference.

G.2.3 Discuss the difficulties of classifying organisms into trophic levels.

Discuss:

Gross Production

Heat

Net Production

Storage

Storage

Heat

Feeding

Examples (Allott study guide pg. 154):1.

2.

3.

4.

G.2.4 Explain the small biomass and low numbers of organisms in higher trophic levels.

G.2.5 Construct a pyramid of energy, given appropriate information. Note: The units are kJ m–2 yr–1.

Trophic Level Energy Flow (kJ m-2 year-1)Producers 4925Primary Consumers 24Secondary Consumers

4

Construct an energy pyramid from this data. Suggest which biome this represents.

G.2.6 Distinguish between primary and secondary succession, using an example of each.

Outline the changes in the gross production of an ecosystem during ecological succession...........................................................................................................................................................................................................................................................................

(2)G.2.7 Outline the changes in species diversity and production during primary succession.

G.2.8 Explain the effects of living organisms on the abiotic environment, with reference to the changes occurring during primary succession. Note: Include soil development, accumulation of minerals and reduced erosion.

G.2.9 Distinguish between biome and biosphere.

G.2.10 Explain how rainfall and temperature affect the distribution of biomes. Note: A climograph showing the biomes in G.2.11 can be used to illustrate the interaction between these two factors.

Changes in Species Diversity Changes in Production

Biotic Changes Abiotic Changes

Copy the graph from pg. 487 of Walpole and color-code it.

Plants called epiphytes grow above the ground on the surface of other plants such as trees. Epiphytes play an important role in rainforests because they can absorb vast amounts of precipitation water (rain and fog), retain minerals effectively and contribute enormous amounts of humus.An investigation was carried out in Ecuador to determine the distribution and abundance of epiphytes in lowland and mountain rainforests. Branch cover was measured for different branch diameters and different branch angles. (The larger the branch diameter, the closer it was to the trunk of the tree.) The results are shown below.

M ou n tain R a in forest L ow lan d R a in forest

40 -18 40 -1817 .9 -9 17 .9 -98 .9 -1 8 .9 -1B ran c h d iam e ter / c m

10 0

80

60

40

20

0

Bra

nch

cove

r / %

B ran c h a ng leho r izo n ta l: 0 – 30 ºin c lin ed : 3 1 –6 0 ºve rtic a l: 6 1 –9 0 º

(a) Outline the percentage of branch cover on horizontal branches of trees in mountain rainforests......................................................................................................................................

(1) (b) Analyse how the branch angle affects the percentage of branch cover in mountain rainforests.

.....................................................................................................................................

..................................................................................................................................... (2)

(c) Compare the percentage of branch cover between mountain rainforests and lowland rainforests for inclined branches...........................................................................................................................................................................................................................................................................

(2) (d) Suggest a reason for the overall difference in branch cover by epiphytes in mountain rainforests and lowland

rainforests...........................................................................................................................................................................................................................................................................

(1) (Total 6 marks)G.2.11 Outline the characteristics of six major biomes. Note: Examples of major biomes could include – desert, grassland, shrubland (chaparral, matorral, maquis and garigue, dry heathlands, fynbos), temperate deciduous forest, tropical rainforest, tundra. The description should be limited to temperature, moisture and characteristics of vegetation.Place the terms desert, grassland, shrubland, temperate forest, tropical rainforest and tundra into the complex Venn diagram.

Ecosystems require an input of energy, water and nutrients to maintain themselves. Nutrients may be reused through recycling within ecosystems.Nutrient cycling within an ecosystem has been studied in many biomes. One factor studied is the mean residence time (MRT), which is the amount of time needed for one cycle of decomposition (from absorption by organism to release after death). The table below gives the mean residence time for certain nutrients in four different biomes. In addition, the plant productivity is also shown. (Plant productivity gives an indication of the quantity of biomass potentially available to consumers.)

Mean residence time / yearsBiome Carbon Nitrogen Phosphorus Potassium Calcium Magnesium Plant

productivity /

g Cm–2

yr–1

Sub-arctic forest 353.0 230.0 324.0 94.0 149.0 455.0 360

Temperate forest 4.0 5.5 5.8 1.3 3.0 3.4 540

Chaparral 3.8 4.2 3.6 1.4 5.0 2.8 270

Tropical rainforest 0.4 2.0 1.6 0.7 1.5 1.1 900

(a) (i) State which nutrient shows the shortest mean residence time in a temperate forest............................................................................................................................

(1) (ii) Identify the biome in which potassium has the longest mean residence time.

...........................................................................................................................(1)

(b) Compare the mean residence time for nutrients in the temperate forest and chaparral...........................................................................................................................................................................................................................................................................

(2)(c) Evaluate the relationship between the mean residence time and plant productivity for the different biomes.

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (2)

(d) Suggest one reason for the difference in mean residence time of nutrients in the tropical rainforest and the sub-arctic forest......................................................................................................................................

(1) (e) Define the term ecosystem.

.....................................................................................................................................

(1)In addition to nutrients, other atmospheric elements may also enter the ecosystem. Radioactive cesium-137 was released into the atmosphere by atomic bomb tests in 1961. The cesium-137 was deposited in the soil and on to plants. The graph shows the amount of radioactivity found in the tissues of lichens (an alga and a fungus growing together), caribou (a member of the deer family) and the Inuit (people of Alaska and Northern Canada) in the Anaktuvuk Pass of Alaska.

In u it

C a rib o u

L ic h e n s

Ju n e1 9 61

Ju n e1 9 6 2

Ju n e1 9 6 3

Ju n e1 9 6 4

Ju n e1 9 6 5

Ju n e1 9 6 6

D ec D ec D ec D ec D ec

In c reas in g ra d io a c tiv ity/ n C i g – 1

(f) Describe the level of cesium-137 in the Inuit from 1962 through to 1965...........................................................................................................................................................................................................................................................................

(2)(g) The three organisms form a food chain. Deduce the trophic level of

(i) lichens; ......................................................................................................(ii) the Inuit. .......................................................................................................

(2)(h) Suggest a reason for the difference in the amount of cesium-137 found in lichens, caribou and the Inuit.

.....................................................................................................................................

.....................................................................................................................................(1) (Total 13 marks)

G.3.1 Calculate the Simpson diversity index for two local communities. Note: Teachers are strongly advised to make students collect actual data. This is an opportunity to use the graphic display calculator and spreadsheets.

Simpson’s index is given by the following equation:

1

1nn

NND

where:D = the diversity index, N = the total number of all species found and n = the number of individuals of a particular species. (i) State what would happen to this index if the numbers of one species increased but the total number of

species stays the same............................................................................................................................

(1) (ii) State what a high value of D suggests about an ecosystem.

...........................................................................................................................(1)

G.3.2 Analyse the biodiversity of the two local communities using the Simpson index.

G.3.3 Discuss reasons for the conservation of biodiversity using rainforests as an example. Note: Reasons should include ethical, ecological, economic and aesthetic arguments. Aim 8: There are environmental issues affecting the whole planet and also ethical issues involved in conservation that could be raised here.

G.3.4 List three examples of the introduction of alien species that have had significant impacts on ecosystems. Note: Choose one example of biological control, and one example each of accidental and deliberate release of invasive species.

G.3.5 Discuss the impacts of alien species on ecosystems. Note: Limit the discussion to inter-specific competition, predation, species extinction and biological control of pest species, with named examples of each.

In the south-west of the USA, dams were built across rivers in the early 1900s to stop natural flooding. As a result, a non-native tree Tamarix ramosissima (salt cedar) gradually replaced the native Populus deltoides (cottonwood) as the dominant woody species. Flooding is being re-established to reverse the invasion of Tamarix.

Studies were done to investigate the relative competitive abilities at the seedling stage using different densities of the two species. Seedlings were grown in pots at different densities and mixtures of the two species. A three dimensional model was developed to show the effect of the densities of each species on Populus mass (graph A) and height (graph B). Densities represent the number of seedlings per 20-cm-diameter pot.

(a) Considering the pots where Populus is growing without Tamarix, describe the change in mass and height of Populus with increased density of Populus seedlings................................................................................................................................................................................................................................................................................................................................................................................................................

(3) (b) Describe how Tamarix density affects Populus height.

.....................................................................................................................................

.....................................................................................................................................(1)

(c) Suggest two factors that could have allowed Tamarix to dominate in non-flood conditions...........................................................................................................................................................................................................................................................................

(2) (Total 6 marks)

G.3.6 Outline one example of biological control of invasive species. Aim 8: Invasive alien species are such a widespread problem that it will almost certainly be possible to find a good local example. Such species are a real threat to the biodiversity of the planet, with many species facing extinction as a result. The uniqueness and cultural diversity of human populations are also being affected.

Discuss the effects of one named human activity that harms ecosystems and how it might be contained or reduced. Refer to an example other than those increasing the greenhouse effect.

(Total 8 marks)

G.3.7 Define biomagnification.

G.3.8 Explain the cause and consequences of biomagnification, using a named example. Note: Examples can include biomagnification of mercury in fish, and organophosphorus pesticides, DDT or TBT (tributyl tin) in ecosystems.

G.3.9 Outline the effects of ultraviolet (UV) radiation on living tissues and biological productivity.

G.3.10 Outline the effect of chlorofluorocarbons (CFCs) on the ozone layer. Note: Details of the chemical reactions are not required.

G.3.11 State that ozone in the stratosphere absorbs UV radiation. Note: There is a limit to UV absorption in the stratosphere. There is no need to mention UV-A, UV-B and UV-C.

G.4.1 Explain the use of biotic indices and indicator species in monitoring environmental change.

Phenologists are biologists who study the timing of seasonal activities in animals and plants, such as the opening of tree leaves and the laying of eggs by birds. Data such as these can provide evidence of climate changes, including global warming.The date in the spring when new leaves open on horse chestnut trees (Aesculus hippocastaneum) has been recorded in Germany every year since 1951. The graph below shows the difference between each year’s date of leaf opening and the mean date of leaf opening between 1970 and 2000. Negative values indicate that the date of leaf opening was earlier than the mean. The graph also shows the difference between each year’s mean temperature during March and April and the overall mean temperature for these two months. The data for temperature was obtained from the records of thirty-five German climate stations.

43210

– 1– 2– 3– 4

1 9 7 0 1 9 8 0 1 9 9 0 2 0 0 0

– 1 5

– 1 0

– 5

0

5

1 0

1 5

D iffe ren c e ind a te o f le a fo p e n in g / d a y s

D iffe ren c e inm ea n te m p e ra tu re

/ ºCK ey :

= te m p e ra tu re= le a f o p e n in g

Ye ar(a) Identify the year in which there was the

(i) earliest opening of horse chestnut leaves;...........................................................................................................................

(1) (ii) lowest mean temperature in March and April.

...........................................................................................................................(1)

(b) Use the data in the graph to deduce the following.(i) The relationship between temperatures in March and April and the date of opening of leaves on horse

chestnut trees............................................................................................................................

(1) (ii) Whether there is evidence of global warming towards the end of the twentieth century.

...........................................................................................................................

........................................................................................................................... (2)

From 1973 onwards phenologists in the Netherlands have been studying a population of great tits (Parus major) in a forest on the Hoge Veluwe. Nest boxes are checked every week to find out when the great tits lay their eggs and how many eggs they lay. Young birds are ringed when they are seven days old, to allow the reproductive success of their parents to be monitored. Great tits feed on arthropods, especially caterpillars. The phenologists found that the date of maximum caterpillar biomass each year in the forest could be estimated accurately using temperature records. The graphs below show the mean date of egg laying and the estimated date of maximum caterpillar biomass for each year from 1973 to 1995.

4 5

3 5

2 5

1 5

57 5

6 5

5 5

4 5

3 5

M ean da te o f eg glay in g / n u m be r o f d ay s

afte r 3 1 M arch

M ean e s tim a ted d a te o fm ax im u m ca te rp illa rb io m ass / n u m b e r o fd ays a fte r 3 1 M arch

19 7 2 1 9 7 6 1 9 8 0 1 9 8 4 1 9 8 8 1 9 9 2 1 9 9 6

Yea r(c) (i) Compare the date of egg laying with the date of maximum caterpillar biomass.

...........................................................................................................................

...........................................................................................................................(1)

(ii) Suggest an advantage to great tits of the difference in dates............................................................................................................................

(1) (d) State the trend, shown in the graph, for the date of maximum caterpillar biomass.

..................................................................................................................................... (1)

There was no statistically significant change in the date of egg laying between 1973 and 1995, but the phenologists found evidence that natural selection will eventually cause a change in the date of egg laying.(e) Explain how natural selection could cause a change in the date of egg laying in the population of great tits in the

forest on the Hoge Veluwe................................................................................................................................................................................................................................................................................................................................................................................................................

(2) (Total 10 marks)

G.4.2 Outline the factors that contributed to the extinction of one named animal species. Note: Examples could include the Carolina parakeet, dodo, passenger pigeon and thylacine (Tasmanian wolf).

Foraminifera are small protozoans found in the sediment of all marine ecosystems. Several thousand species of foraminifera live in the Earth’s oceans. Because a large number of individuals can be found in a small amount of sediment and because they exist worldwide, foraminifera are useful in examining the distribution of species. The bar graph below summarizes data gathered from five coastal regions around North America. Those species occurring in all five regions are considered to be ubiquitous and those species occurring in only one area are considered to be endemic. The species of foraminifera were placed into three classes based on the number of times each species occurred at the five coastal regions.

50 0

40 0

30 0

20 0

10 0

0

O ccu rren ces(n u m b er o f tim es sp ec ies see n in a reg io n )

P ac ific A rc tic A tla n tic G ulf o fM ex ico

C aribb ean

U U U U U

E

E

E

E

E

N um be r o f spe c ies

> 322-321-2

(a) Calculate the percentage of endemic species occurring in the Pacific region......................................................................................................................................

(1) (b) Among the five regions, deduce the region where it would be easiest to find most of the ubiquitous species.

.....................................................................................................................................(1)

(c) Compare the occurrence of endemic species in the Pacific and Caribbean regions......................................................................................................................................

..................................................................................................................................... (2)

(d) Suggest, giving a reason, which of the Pacific, Atlantic or Caribbean regions will have a greater extinction rate...........................................................................................................................................................................................................................................................................

(2) (e) Identify which region has the lowest species diversity.

.....................................................................................................................................(1) (Total 7 marks)

G.4.3 Outline the biogeographical features of nature reserves that promote the conservation of diversity. Note: Limit this to edge effects, size and habitat corridors. Large nature reserves usually promote conservation of biodiversity more effectively than small ones. The ecology of the edges of ecosystems is different from the central areas due to edge effects. An example of an edge effect is the egg-laying habits of the cowbird of the western United States. It feeds in open areas, but it lays its eggs in the nests of other birds near the edges of forests. Fragmentation of forests has led to a considerable increase in cowbird populations because of the increase in forest edge. Wildlife corridors allow organisms to move between different parts of a fragmented habitat, for example, tunnels under busy roads.

G.4.4 Discuss the role of active management techniques in conservation. Note: Use a local example wherever possible to illustrate this.

The Kluane boreal forest ecosystem project was a large scale ten year experimental manipulation of food and predators on arctic ground squirrel population (Spermophilus parryii plesius).Three areas were set up:

a food addition area a predator exclusion area a food addition area enclosed within a predator exclusion area.

The areas were monitored from 1986 to 1996. In spring 1996 all fences were dismantled and food addition was stopped.As a further experiment, spring and summer mark-recapture population estimates of the squirrels were conducted from spring 1996 to spring 1998. The results for these two years are shown below. The areas are labelled according to the

conditions imposed during the previous ten years.

3 0

2 5

2 0

1 5

1 0

5

0S prin g1 9 9 6

S prin g1 9 9 7

S prin g1 9 98

S u m m e r19 9 6

S u m m er19 97

Squi

rrel

s he

ctar

e–1

C o n tro lP re da to r ex c lu sio nF o o d a d d itio nF o o d a d d itio n p lusp re d a to r e x c lu s io n

(a) State the squirrel population in the food addition plus predator exclusion area in spring 1996......................................................................................................................................

(1)(b) Describe the effect of ending food addition on the squirrel population.

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (2)

(c) Scientists believed that the number of ground squirrels in the boreal forests was limited by an interaction between food and predators that acted primarily through changes in reproduction. Using the data, discuss this hypothesis.....................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................

(3) (Total 6 marks)

G.4.5 Discuss the advantages of in situ conservation of endangered species (terrestrial and aquatic nature reserves).

G.4.6 Outline the use of ex situ conservation measures, including captive breeding of animals, botanic gardens and seed banks.

Understanding the ecological mechanism that causes extinction is fundamental to conservation as not all organisms are threatened by the same factors. A total of 1012 threatened bird species in 95 families were studied to see how they were threatened by different factors:

habitat loss persecution by humans and introduced predators other factors (introduced competitors, hybridization and disease) and unknown risk factors.

Scientists investigated the relationship between body size and the risk of extinction, both due to habitat loss and to persecution/predation. Birds were classified as small (mean body mass 1 to 1000 g) and large (mass greater than 1000 g). The results are shown in the pie chart and bar char++++++++++

ts below.

6543210

6543210

E x tin ction r isk fro m h a b ita t lo ss

E x t in ctio n r isk fro m persecut io n /p red a tion

P erce n tag e o fsp ec ies in

fam ily a t r isk

P erce n tag e o fsp ec ies in

fam ily a t r isk

S m a ll

S m a ll

L arg e

L arg e

B o d y s ize

B o d y s ize

P ercen ta g e o f a ll 1 0 1 2 spec iesth rea ten ed b y ea ch ty p e of fa c to r

2 0 %

1 0 %

2 5 %

4 5 %

H ab ita t lo s s o n ly

H ab ita t lo s s a n d p red a tio n / p e rsec u tio n

P re d a tio n / p e rse cu tio n o n ly

O th er / u n k n o w n

(a) (i) State the percentage of species affected in some way by habitat loss............................................................................................................................

(1) (ii) Calculate the approximate number of bird species threatened by predation / persecution only.

...........................................................................................................................

........................................................................................................................... (1)

(b) State two factors that could have caused habitat loss.1 ..................................................................................................................................2 ..................................................................................................................................

(2) (c) Outline, using the bar charts, the effect of body size on the risk of extinction.

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (2)

(d) Discuss the methods of conservation that would avoid the extinction of large species................................................................................................................................................................................................................................................................................................................................................................................................................

(3) (Total 9 marks)

G.5.1 Distinguish between r-strategies and K-strategies. Note: There are organisms that display extreme r- or K-strategies, but most organisms have life histories that are intermediate on the continuum. Some organisms such as Drosophila switch strategies depending on environmental conditions.

G.5.2 Discuss the environmental conditions that favour either r-strategies or K-strategies. Note: In a predictable environment, in order to maximize fitness, it pays to invest resources in long-term development and long life (K-strategy). In an unstable environment, it is better to produce as many offspring as quickly as possible (r-strategy). Of concern is that ecological disruption favours r-strategists such as pathogens and pest species.

G.5.3 Describe one technique used to estimate the population size of an animal species based on a capture–mark–release–recapture method. Note: Various mark-and-recapture methods exist. Knowledge of the Lincoln index (which involves one mark–release–recapture cycle) is required, as follows. Although simulations can be carried out (for example, sampling beans in sawdust), it is much more valuable if this is accompanied by a real exercise on a population of animals. The limitations and difficulties of the method can be fully appreciated, and some notion of the importance of sample size can be explained. It is important that students appreciate the need for choosing an appropriate method for marking organisms.

The capture-mark-release-recapture method was used to determine the number of Sandhill Cranes (Grus canadensis nesiotes), an endangered species of bird, living on an island.The following data were obtained:

number of Sandhill Cranes initially caught, marked and released = 22 total number of Sandhill Cranes caught in second sample = 14 number of marked Sandhill Cranes in the second sample = 2

What is the population size of the Sandhill Cranes on the island?A. 77B. 154C. 308D. 616

Describe one method for determining the population of a motile animal species and one different method for determining the population of a plant species.

(Total 7 marks)

On a field trip a group of students was asked to estimate the size of the population of a small, nocturnal ground dwelling mammal, the long-nosed bandicoot (Perameles nasuta). The bandicoot feeds on invertebrates and plant material found by digging pits 5 cm deep in the ground with its front legs.

(a) (i) State the name of an appropriate technique to estimate the population sizeof P. nasuta............................................................................................................................

(1)(ii) Describe this method of estimating the population size of P. nasuta.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

........................................................................................................................... (3)

(b) Deduce, with reasons, the trophic level of P. nasuta in food chains...........................................................................................................................................................................................................................................................................

(2) (Total 6 marks)

G.5.4 Describe the methods used to estimate the size of commercial fish stocks.

Discuss the difficulties in obtaining quantitative data needed to promote fish conservation.............................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................

(Total 3 marks)G.5.5 Outline the concept of maximum sustainable yield in the conservation of fish stocks. Aim 8: There are clear ethical, social, environmental and economic issues here, some of which conflict with each other. TOK: Data about fish stocks is very difficult to obtain and interpret, allowing huge differences in views on what is sustainable. In addition to fishing, whale hunting is an area where there is widespread disagreement about what is sustainable and also what is ethical.

The Food and Agricultural Organization (FAO) gathered information to determine if marine ecosystems were being damaged by overfishing. The total fish captured in each of three oceans from the years 1960 to 2000 was compared to the overall world marine capture.

10 0908070605040302010

0

F ish ca tch /× 1 0 ton n es6

1 9 6 0 1 9 7 0 19 8 0 1 9 9 0 20 0 0Ye a r

W o rld m a rin efish c a p tu re

P a c ific

O ce an

A tla n tic

O c ean

In d ian

O ce an

(a) Calculate the percentage of the world catch that came from the Atlantic Ocean in 1990...........................................................................................................................................................................................................................................................................

(1)(b) Compare the data from the Pacific Ocean with that from the Atlantic Ocean.

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (3)

(c) Suggest one reason in each case for the change in the quantity of fish captured in the Atlantic and Indian Oceans from 1980 to 1990.Atlantic Ocean: .....................................................................................................

......................................................................................................Indian Ocean: ......................................................................................................

......................................................................................................(2) (Total 6 marks)

G.5.6 Discuss international measures that would promote the conservation of fish. Aim 8: As in G.5.5, there are many issues involved here, and there is a chance to discuss the need for international agreement and cooperation in a world that is largely governed at a national level, with large areas of ocean under no government control at all. TOK: This is a chance to discuss decision-making, based partly on scientific evidence that has to take place at an international level.

Destruction of subtidal and intertidal kelp (seaweed) and seagrass beds has been observed over a wide geographical range. Removal of sea urchins (Strongylocentrotus sp.) by experimental manipulation and accidental oil spill has resulted in the rapid development of marine vegetation. The presence and absence of kelp beds has a major effect on the structure of the marine community.A survey was carried out of two of the western Aleutian Islands with and without sea otters (Enhydra lutris). Sea urchin size,

density and biomass were measured. Densities and biomass were recorded per 0.25 m2

. Data was collected from Amchitka Island (with sea otters) and Shemya Island (without sea otters).

(a) (i) State the diameter of sea urchins with the most frequent biomass on Amchitka Island...........................................................................................................................

(1) (ii) Suggest, giving a reason, which island would have the oldest sea urchins.

..........................................................................................................................

..........................................................................................................................(1)

(b) Compare the sea urchin densities and biomass on Shemya Island and Amchitka Island.........................................................................................................................................................................................................................................................................

(2) (c) Deduce the trophic level of the sea urchins in this marine community.

....................................................................................................................................

(1) (d) Explain the observed differences in sea urchin populations on the two islands.

....................................................................................................................................

....................................................................................................................................

....................................................................................................................................(2) (Total 7 marks)

Copepods are very small crustaceans and an important component of plankton in the Arctic sea ice. The distribution of copepods, which feed on microalgae, can be related to the food and predators. The biomass of microalgae was measured and the concentration of chlorophyll a was calculated. The graphs below show how the concentration of chlorophyll a and copepods change with depth.

Dep

th /

m M icroa lg a e

C h lo ro p hy ll a / m g m – 3

Dep

th /

m

C o pe p o d s

R e la tiv e nu m b ers

(a) State the amount at a depth of 30 m below sea level of(i) chlorophyll a;

..........................................................................................................................(ii) copepods.

..........................................................................................................................(2)

(b) Describe the distribution of microalgae......................................................................................................................................................................................................................................................................... (2)

(c) Discuss factors that could affect the distribution of copepods.................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................

(3)(Total 7 marks)

Blue crabs (Callinectus sapidus) hunt clams in river streams. In response to being attacked the clams release chemicals. The hunting behaviour of the blue crabs was studied by recording their movements after the release of the chemical which was visualized by adding a dye (noted by shading in the figure below). The behaviour was studied and recorded under three

different water velocities (expressed in cm s–1

).Each graph below shows the movement of a single crab recorded at 1 s intervals, as it moves upstream towards the source of the chemical.

C ra b A

C ra b B

C ra b C

Late

ral m

ovem

ent /

cm

Water v e lo c ity = 4 .2 cm s– 1

Wa te r v e lo c ity = 1 0 cm s –1

Wa te r v e lo c ity = 2 5 cm s –1

D is tan ce d o w n s trea m fro m so u rc e / cm(a) Identify which crab shows the greatest lateral movement.

....................................................................................................................................(1)

(b) Calculate the greatest speed of crab movement at 150 cm from the source of the chemical.....................................................................................................................................

(1) (c) Compare the effect of water velocity on the hunting behaviour of blue crabs.

....................................................................................................................................

.................................................................................................................................... (2)

(d) Discuss two other factors that could influence the outcome of this experiment.................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................

(2)(Total 6 marks)

The horseshoe crab (Limulus polyphemus) lay their eggs in the sand on beaches in the intertidal zone. The nesting site is selected on the basis of distance above the mean high tide line, oxygen concentration and temperature of the sand. Egg development was assessed after 10 days and recorded as an arbitary unit, the higher the value the more developed the eggs were. The “0 m” beach distance is based on the mean high tide line.

(a) State the optimum distance above the high tide line for egg laying.....................................................................................................................................

(1) (b) Describe the effect of oxygen concentration and temperature on egg development.

....................................................................................................................................

....................................................................................................................................

.................................................................................................................................... (2)

(c) Scientists believe that egg development was influenced by oxygen concentration, temperature of the sand and distance from the mean high tidal line. (i) Evaluate this study with respect to these three factors.

..........................................................................................................................

..........................................................................................................................

..........................................................................................................................

..........................................................................................................................

.......................................................................................................................... (2)

(ii) State one other possible factor that might influence egg development.....................................................................................................................................................................................................................................................

(1) (Total 6 marks)

A study was conducted on how cattle grazing affects the water content of soils. One area studied was a pasture of alfalfa (Medicago sativa). A special probe was used to take measurements of soil water to depths of 300 mm. The range of measurements obtained were used to calculate the total soil water content expressed in mm. Results from part of the study during the growing season for the year 2000 are shown below.

To ta l so il w a te r / m m

12 5

10 0

75

50

25 1 2 0 14 0 1 6 0 1 8 0 2 0 0 22 0 2 4 0 2 6 0 2 8 0

D ay o f th e yea r

K ey : g raz ed un -g raz ed

(a) State the overall trend in total soil water content during the study period.....................................................................................................................................

(1)(b) Identify the day on which the difference in total soil water content of grazed and un-grazed areas was greatest.

....................................................................................................................................

(1) (c) Discuss the effects of grazing on the total soil water content.

....................................................................................................................................

....................................................................................................................................

....................................................................................................................................

....................................................................................................................................

.................................................................................................................................... (4) (Total 6 marks)

The relationship between climatic factors with plant flowering and fruiting was recently investigated in the rainforests of the Philippines. In that tropical region important climatic factors include the amount of rainfall and sunlight. Typhoons (massive storms with powerful winds and torrential rainfall) occur between July and November. Solar radiation reaches a maxim um in April and September. The graph below shows the numbers of flowering trees () and fruiting trees (---). The area under the dotted line shows the number of fruiting trees with each of five seed dispersal mechanisms.

(a) Compare the flowering pattern with the fruiting pattern in 1996.........................................................................................................................................................................................................................................................................

(2)(b) Discuss the influence of solar radiation on flowering patterns during the four years.

....................................................................................................................................

....................................................................................................................................

.................................................................................................................................... (2)

(c) Explain the timing of seed dispersal by gravity and wind.............................................................................................................................................................................................................................................................................................................................................................................................................

(2) (Total 6 marks)Magellanic penguins (Spheniscus magellanicus) live and breed near the coast of Argentina. However, their colonies are a long way from the open sea where they hunt for fish. They cannot fly so have to swim to the feeding grounds. A study investigated how the water currents due to high and low tides affected their journey to and from their colonies. The results are shown below.

C u rren t fro m co lo n y

C u rren t to co lo n y

C u rren t fro m co lo n y

P en guins / nu m ber

7 0

6 0

5 0

4 0

3 0

2 0

1 0

0 0 6 :00 12 :00 18 :00 2 2 :00 M o rn in g E v en in g

Tim e o f d ay / h ou r

K ey : d epa rting fro m co lo n y a rriv in g a t co lon y(a) (i) Identify the number of penguins departing from the colony at 06:00 hours.

..........................................................................................................................(1)

(ii) Identify the time of day when most penguins arrive at the colony...........................................................................................................................

(1)(b) Describe the pattern of movement of penguins departing from the colony between 06:00 hours and 22:00 hours.

....................................................................................................................................

....................................................................................................................................

....................................................................................................................................

(2) (c) Suggest why there is little movement in either direction between 14:00 hours and 16:00 hours.

....................................................................................................................................

....................................................................................................................................(2)

The study also investigated the range of swim speed for one penguin when out hunting in the open sea.

S w im s p e ed / m s -1

4 .0

3 .5

3 .0

2 .5

2 .0

1 .5

1 .0

0 .5

0 .0 0 6 :0 0 11 :0 0 1 6 :0 0

Tim e o f d ay / h o u r (d) Calculate the greatest difference in swim speed during the study.

.................................................................................................................................... (1)

(e) Suggest two reasons for the changes in swim speed of the penguin during the period of time of the study.............................................................................................................................................................................................................................................................................................................................................................................................................

(2) The diagram below shows part of the coastline.

p o in t Y L a n d O pen se a

w a lk in g d is ta n ce 1 7 5 m

p o in t X

(f) A penguin uses 88 joules of energy to walk one metre. Calculate the energy used to walk from point X to point Y.....................................................................................................................................

(1) (g) The penguin uses more energy swimming. Suggest one reason why most penguins actually swim rather than walk

from point X to point Y.....................................................................................................................................

(1) (h) Explain why penguins have many mitochondria in the muscles used for swimming.

....................................................................................................................................

.................................................................................................................................... (2) (Total 13 marks)

Conservationists noticed that the number of red squirrels (Sciurus vulgaris) in Wales was declining, and the number of a newly introduced species, the North American grey squirrel (Sciurus carolinensis), was increasing. In 1998, a project was started to reduce the number of grey squirrels in 244 hectares of woodland in Wales. The graph below shows the number of grey squirrels in 1998 and the number of red squirrels in 1999, 2000 and 2002. The data was collected at eight different sites (A–H).

S q u irre l d e ns ity / n u m ber p e r h e cta re

1 .21 .11 .00 .90 .80 .70 .60 .50 .40 .30 .20 .10 .0

K ey : G re y 1 9 9 8 R e d 1 99 9 R e d 2 0 00 R e d 2 0 02

A B C D E F G H

S ite(a) Identify the year in which the greatest number of red squirrels was found in site E.

....................................................................................................................................(1)

(b) State the number of sites that had a greater density of red squirrels in 2002 compared with the density of grey squirrels in 1998.....................................................................................................................................

(1)(c) Discuss the hypothesis that decreasing the density of grey squirrels after 1999 led to an increase in the density of red

squirrels in the following years.............................................................................................................................................................................................................................................................................................................................................................................................................

(3) (d) Outline the relationship between grey squirrels and red squirrels assuming that they occupy the same niche.

....................................................................................................................................

.................................................................................................................................... (3) (Total 8 marks)

Students investigated a community of trees by sampling a total area of 20 000 m2

.Species Number of plants

Douglas fir (Pseudostuga menziesii) 30Big Leaf Maple (Acer macrophyllum) 60

Grand Fir (Abies grandis) 240(a) Calculate the plant density for the Grand Fir.

....................................................................................................................................(1)

(b) Describe the method used to collect this data.............................................................................................................................................................................................................................................................................................................................................................................................................

(3) (c) Explain why populations show a sigmoidal growth curve.

....................................................................................................................................

....................................................................................................................................

.................................................................................................................................... (3) (Total 7 marks)

A population of bighorn sheep (Ovis canadensis) on Ram Mountain in Alberta, Canada, has been monitored since the 1970s. Hunters can buy a licence to shoot male bighorn sheep on the mountain. The large horns of this species are very attractive to hunters, who display them as hunting trophies.Most horn growth takes place between the second and the fourth year of life in male bighorn sheep. They use their horns for fighting other males during the breeding season to try to defend groups of females and then mate with them. Younger males below the age of 6 are rarely able to compete with older males and so have fewer offspring.The graph below shows the size of the bighorn sheep population on Ram Mountain.

P op u la tio n s iz e

1 6 0

1 2 0

80

40

0 1 9 7 0 1 9 7 5 1 9 8 0 19 8 5 1 9 9 0 19 9 5 2 0 0 0 20 0 5

Year(a) Outline the trends in the population of bighorn sheep on Ram Mountain.

.....................................................................................................................................

..................................................................................................................................... (2)

The length of a male’s horns is strongly influenced by its genes. It is therefore possible to predict the length of the horns of the future offspring of a male. An index of predicted horn length for the future offspring of each male on Ram Mountain has been calculated. Negative values indicate offspring with smaller horns than the mean of the population. Positive values indicate horns larger than the mean of the population. (b) Suggest one type of factor apart from genes, that could affect the length of a male’s horns.

.....................................................................................................................................(1)

The scattergraph below shows the relationship between the age to which a male lived (longevity) and the predicted horn length index of the male.

L o n g ev ity / ye a rs

1 4

1 2

1 0

8

6

4

–4 – 2 0 2 4 6 8

P red ic ted h o rn len g th ind ex

(c) State the most frequent longevity (the mode)......................................................................................................................................

(1)(d) (i) Outline the relationship between longevity and the predicted horn length index of the males.

...........................................................................................................................

........................................................................................................................... (1)

(ii) Suggest a reason for the relationship.

...........................................................................................................................

........................................................................................................................... (1)

The graph below shows the mean horn length of males on Ram Mountain, between 1975 and 2002.M

ean

horn

leng

th /

cm8 0

7 0

6 0

5 0

4 0

0 1 9 7 0 1 97 5 1 9 8 0 1 98 5 1 99 0 1 99 5 2 00 0 2 00 5

Ye ar(e) Explain the change in horn length shown in the graph in terms of the longevity of the males, the number of offspring

that they produce and your understanding of the process of evolution................................................................................................................................................................................................................................................................................................................................................................................................................

(3) (f) Suggest how the change in the size of horns could be reversed.

..................................................................................................................................... (1) (Total 10 marks)

A coral polyp is a marine organism, characterized by a hard skeleton. Coral reefs are colonies of numerous individual polyps. Coral polyps often form close associations with tiny plants such as algae. The algae, which live within the tissues of the polyp, give the coral its unique colour. The algae receive nutrients from their host and provide the host with a food source in return. When coral undergoes environmental stress it expels algae from its polyps and the coral appears white. This process is called “coral bleaching”.The graph below indicates the number of coral reef areas showing bleaching over a 20-year period off the coast of Australia. The arrows indicate the occurrence of El Niño, an event that brings effects such as an increase in water temperature around the coral.

(a) Outline the trend in the number of coral reef areas showing bleaching over the period 1979 to 1998.......................................................................................................................................................................................................................................................................

(2)

(b) Discuss the effect of El Niño on the incidence of coral bleaching.............................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................

(3) (c) Scientists suggest that El Niño may be increasing in frequency. Suggest the impact that this might have on coral

bleaching....................................................................................................................................

(1) Sargassum, a variety of brown algae that exists as a floating canopy above coral, was studied to determine its impact on the rate of coral bleaching. The graph below shows the percentage of bleached corals on two reefs, Goold Island and Great Palm Island, with the Sargassum canopy left intact and with the Sargassum canopy removed.

P e rc en ta ge o fcora ls b lea ch e d

7 0

6 0

5 0

4 0

3 0

2 0

1 0

0

K ey :

Sarg a ssu m rem o ve d

Sarg a ssu m le ft in tac t

G o o ld Is lan d G re a t P a lm Is la n d(d) Identify the percentage of corals bleached near Great Palm Island when Sargassum is left intact.

................................................................................................................................... (1)

(e) Compare the effect of Sargassum removal on the amount of coral bleaching at the two locations..........................................................................................................................................................................................................................................................................................................................................................................................................

(2) (f) With reference to the effects of El Niño and Sargassum removal, suggest two abiotic factors which might contribute

to coral bleaching.1. .........................................................................................................................2. .........................................................................................................................

(2) (g) Suggest, giving a reason, how one human impact might increase the degree of coral bleaching.

...................................................................................................................................

...................................................................................................................................

................................................................................................................................... (2)(Total 13 marks)

Ornithologists studied the size of birds of prey and compared them with the sizes of their prey. The diagram below shows the mean results for four species of hawk.

H aw k m a ss / g

1 0 0 0

1 00

1 0 1 00 1 00 0P rey m ass / g

in d ic a te s m a le h aw k sin d ic a te s fem a le h aw k s

K e y :

A cc ip itercoo pe r ii

A cc ip iter s tr ia tu s

A cc ip iter n isu s

A cc ip iter gen tile s

(a) State the relationship between the mass of the hawks and the mass of their prey....................................................................................................................................

(1) (b) (i) Describe the differences between the masses of the hawks and the masses of their prey.

........................................................................................................................

........................................................................................................................ (2)

(ii) Explain how the difference in the mass between the hawks and their prey can result in a lower biomass at higher trophic levels.................................................................................................................................................................................................................................................

(1) (c) Compare the masses of the different sexes of these species.

...................................................................................................................................

................................................................................................................................... (1)

(d) Suggest reasons for the differences in the masses of the male and the female hawks..........................................................................................................................................................................................................................................................................................................................................................................................................

(2) (Total 7 marks)The biodiversity of Costa Rican salamanders was studied over a range of altitudes. The salamanders belong to three genera: Nototriton, Oedipina and Bolitoglossa. Nototriton includes very small animals (less than 40 mm), Oedipina has an average size of 60 mm and Bolitoglossa is a diversified genus including B. pesrubra which is less than 65 mm to B. nigrescens which is about 95 mm.

35 00

30 00

25 00

20 00

15 00

10 00

5 00

A ltitu d e / m

N. pic

adoi

O. pse

udouni

formis

O. uni

formis

B. stri

atula

B. col

onnea

B. rob

usta

B. gra

cilis

B. soo

yorum

B. nig

rescen

s

B. cer

rosens

is

B. pes

rubra

S a la m a nd e r sp ec ies

(a) Identify the range of altitude at which B. cerroensis can be found.....................................................................................................................................

(1) (b) Identify the altitude at which the greatest diversity of salamanders can be found.

....................................................................................................................................(1)

(c) Compare the distribution of Bolitoglossa and Oedipina.............................................................................................................................................................................................................................................................................................................................................................................................................

(2)(d) Evaluate the evidence provided by the data for altitude as a factor in the ecological niches of the salamanders.

....................................................................................................................................

....................................................................................................................................

....................................................................................................................................

.................................................................................................................................... (3) (Total 7 marks)

Fiddler crabs (Uca beebei) live in mixed-sex colonies on the intertidal mudflats on the Pacific coast of Central and South America. Both sexes defend their burrows and forage for food at the surface during low tide. The population of fiddler crabs has an equal number of males and females. The male crabs have one large claw and one small claw. Female crabs are lighter

in colour and have two small claws.Great-tail grackles (Quiscalus mexicanus), a large bird, are a common predator of fiddler crabs. Grackles hunt by running straight at the crabs or by running past them then turning sharply back (angled run) to dive on the crabs. Research was undertaken to study the behaviour and predation of the fiddler crabs. The results are shown in the graph below.

P red a tio n o f F id d ler C ra b s b y G rea t–Ta il G ra ck les

F req u e n cy

1 2 0

1 0 0

8 0

6 0

4 0

2 0

0

S tra ig h t ru n A n g le d ru n K ey :

M a le c ra b s

F e m ale c ra b s

A ttem p ts S u c ce ss fu l A tte m p ts S u cc e ss fu l(a) Calculate the percentage predation success when grackles hunt male crabs using a straight run.

.................................................................................................................................... (1)

(b) Determine the percentage difference in the number of attempts made on female crabs by grackles using a straight run versus an angled run.....................................................................................................................................

(1)(c) Outline the predation success of grackles when using a straight run versus an angled run.

....................................................................................................................................

....................................................................................................................................

.................................................................................................................................... (2)

(d) Suggest a reason for the difference in predation success of the grackles.........................................................................................................................................................................................................................................................................

(1) (Total 5 marks)Cyanobacteria (photosynthetic organisms) show a circadian rhythm or “biological clock” in which their biological activities are linked with the day-night cycle. When cyanobacteria are grown on or close to their optimum circadian rhythm, their fitness (development, growth and longevity) is improved.Researchers investigated competition between cyanobacteria with different optimal circadian rhythms. Wild type (most frequent genotype) cyanobacteria and two mutant strains ― SP22 and P28, were placed in dishes containing a nutrient gel. The cyanobacteria were exposed to two different light-dark cycles (for a period of 27 days): 11 hours light then 11 hours dark (LD 11:11), or 15 hours light followed by 15 hours dark (LD 15:15). The graphs below show the initial and final composition of cyanobacteria in the dishes.

G ra p h A

Perc

enta

ge o

f stra

in in

mix

ture

1 0 07 55 02 5

0

S p 2 2 (c ircad ian rh y th m = 2 3 h o u rs)

w ild typ e (c ircad ian rh y th m = 2 5 h o u rs )

G ra ph B1 0 0

7 55 02 5

0

P 2 8 (c ircad ian rh y th m = 3 0 h o u rs)

w ild typ e (c ircad ian rh y th m = 2 5 h o u rs )

pG ra h C1 0 0

7 55 02 5

0 fin a l in i tia l f in a l co m p o sit io n co m p o s it io n c o m p o s itio n afte r 2 7 d ay s a fte r 2 7 d a y s

L D 11 :11 L D 1 5 :1 5

S p 2 2 (c ircad ian rh y th m = 2 3 h o u rs)

P 2 8 (c ircad ian rh y th m = 3 0 h o u rs)

(a) State the initial composition of the P28 strain in graph B.....................................................................................................................................

(1)

(b) Compare the wild type strain in competition against the mutant strains(i) when exposed to the LD 15:15 cycle;

..........................................................................................................................(1)

(ii) when exposed to the LD 11:11 cycle...........................................................................................................................

(1) (c) A new strain of cyanobacteria with a circadian rhythm of 27 hours was isolated. Predict, giving a reason, what would

happen if this new strain was grown with the wild type when exposed to the LD 15:15 cycle.............................................................................................................................................................................................................................................................................................................................................................................................................

(2) (d) Explain whether or not this data supports the competitive exclusion principle.

....................................................................................................................................

....................................................................................................................................

.................................................................................................................................... (2) (Total 7 marks)

In parts of Asia, phosphorus deficiency in the soil is thought to be the reason for poor rice yields. In Laos, Thailand and the Philippines researchers cultivated rice with varying quantities of phosphorus fertilizer. When the crops were ready for harvesting the phosphorus uptake of the plants was measured. This was compared to both the dry biomass of rice grains and of the whole rice plants.

(a) State the biomass of the whole rice plants when the phosphorus uptake was 14 kg ha–1

......................................................................................................................................

(1) (b) State the relationship between phosphorus uptake and the biomass of the whole rice plants.

.....................................................................................................................................

.....................................................................................................................................(1)

(c) Define the term harvestable dry biomass...........................................................................................................................................................................................................................................................................

(1) (d) Discuss, with reference to both the graph and your knowledge of plant cultivation, whether Asian farmers should be

advised to purchase phosphorus fertilizers to increase crop yield................................................................................................................................................................................................................................................................................................................................................................................................................

(3) (Total 6 marks)Conservationists identified twenty-four wilderness zones in the world. A wilderness is defined as an area greater than 10 000

km2

, with a human population of less than five inhabitants per km2 and is mostly unspoiled, therefore, retaining its natural condition. Various activities threaten the biodiversity of these wilderness zones. Each wilderness zone was identified as belonging to one of six major biomes. The chart below shows the number of wilderness zones belonging to each biome and the number under threat.

(a) State how many of the activities threaten all of the biomes......................................................................................................................................

(1)(b) Identify one activity that threatens all desert wilderness zones.

.....................................................................................................................................(1)

(c) Compare the effects of pollution and climate change on the biomes................................................................................................................................................................................................................................................................................................................................................................................................................

(3) (d) Suggest how fire affects biodiversity.

..................................................................................................................................... (1) (Total 6 marks)

A long-term study examined the effect of ocean climate on the foraging (hunting) success of northern elephant seals (Mirounga angustirostris). Throughout their pregnancy, female northern elephant seals capture fish for food, which is converted to food reserves for milk production. Seal pups feed solely on their mother’s milk so a pup’s mass correlates positively with the mother’s success at foraging.The Pacific Ocean fluctuates between extended warmer and colder periods. These bring with them changes identified broadly as either an “anchovy regime” (ocean temperatures cooler than normal, increased nutrient supply, high catches of anchovies) or a “sardine regime” (ocean temperatures warmer than normal, overall low productivity, low anchovy but high sardine catch).The graph below shows the relationship between weaning mass of northern elephant seal pups and anchovy and sardine regimes.

(a) Calculate the greatest difference in weaning masses during the sardine regime.Greatest difference : ................................................................................................

(1)(b) Describe the relationship between mean weaning mass and the sardine and anchovy regimes from 1975 to 2004.

....................................................................................................................................

.................................................................................................................................... (1)

(c) Discuss what type of ocean water temperatures result in more successful foraging by female northern elephant seals.................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................

(3) (Total 5 marks)Two species of sea snakes, Laticauda laticaudata and Laticauda colubrina, spend most of their lives living in the sea. They must be able to move, hunt and survive in the water, but for short periods they need to come ashore to breed. They inhabit some of the Pacific islands which have low coral cliffs that the snakes need to climb in order to get onto dry land for courtship, mating and laying eggs.Figure 1 Diagram to show a cross-sectional view of cliff used in the study

H e ig h t

ve g e ta tio n

2 .3 m

se a lev e l

The scientists studied the ability of snakes to climb the low cliff. They measured the body mass of the snakes and relative strength of the snakes. The mean results are shown in the bar charts below.

Bod

y m

ass/

g

2 5 0

2 0 0

1 5 0

1 0 0

5 0

0 Mus

cle

stre

ngth

/ ar

bitra

ry u

nits 2 5

2 0

1 5

1 0

5

0F em a le s M a le s F em a le s M ales

K e y: L . la ticau da ta L . co lu brin a(a) State which sex of snake has the greater mean mass.

.....................................................................................................................................(1)

(b) State which species of snake is the strongest......................................................................................................................................

(1) (c) The error bars represent standard deviation. Deduce which groups of snakes show the greatest variability in body

mass......................................................................................................................................

(1) (d) For L. colubrina calculate the difference between the strength of the male and the female snakes.

.....................................................................................................................................

..................................................................................................................................... (1)

The scientists placed male snakes onto the coral cliff near its base. They measured their ability to hold onto the coral cliff. The L. colubrina males climbed much faster than the males of L. laticaudata. The graph below shows the ability of snakes to cling to the coral cliff.

S n ak es still c lin g in gto th e c liff / %

10 0

80

60

40

20

0

K ey :

L . co lub rin a L . la ticau d ata

0 20 40 60 8 0 10 0 1 2 0Tim e / s econ ds

(e) (i) Compare the ability of the two species of snake to cling to the cliff.......................................................................................................................................................................................................................................................

(2) (ii) Suggest two reasons for the difference in the ability of the snakes to cling to the cliffs for 120 seconds.

...........................................................................................................................

........................................................................................................................... (2)

(f) Discuss the advantages and disadvantages of body mass in these two species of snake.....................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................

(3) (Total 11 marks)The mold Penicillium expansum causes serious crop loss of apples and pears during storage and packing. The graphs below show the density of P. expansum spores on normal skin, damaged skin and lenticels (small air pores allowing gaseous exchange) of apples. The experiments show the results at two humidity levels over a four day period.

H ig h h u m id ity L o w h u m id ity1 0 0 0

1 0 0

1 0

1

1 0 0 0

1 0 0

1 0

19 64 82 41 240 9 64 82 41 240

Tim e / h T im e / h

Log

spor

es / c

m10

2

Log

spor

es / c

m10

2

K ey : d e n s ity o f sp o re o n n o rm a l sk ind e n s ity o f sp o re o n d am ag e d sk ind e n s ity o f sp o re o n len tice ls

(a) State the time taken for spores on the skin to reach a density of 100 spores/cm2

at high humidity.......................................................................................................................................

(1) (b) Compare the density of spores on normal skin with spores on lenticels for apples stored at high humidity.

......................................................................................................................................

......................................................................................................................................

...................................................................................................................................... (2)

(c) Discuss whether apples should be stored at high humidity or low humidity.........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................

(3) (Total 6 marks)

Scientists examined the fauna found in the North Sea and measured the relative abundance of a number of species over a period of time at three locations. The depth of water at all the locations was similar although their distance to the coast varied. The North Sea is surrounded by densely populated and industrial European countries. The species were divided into four broad groups:

I. disturbance sensitiveII. disturbance indifferentIII. disturbance tolerantIV. opportunistic

The results are shown below. No measurements were taken in the months where there is no column.100

8 0

6 0

4 0

2 0

0100

8 0

6 0

4 0

2 0

0100

8 0

6 0

4 0

2 0

0

L oca tio n A

L oca tio n B

L oca tio n C

A b un da n c e / %

A b un da n c e / %

A b un da n c e / %

S O N D J F M A M J J A S O N D J F M A M

K e y :

G rou ps

I

IIII IIV

2 00 0 2001 2 00 2Tim e in m on th s a n d y ea rs

(a) State the lowest relative abundance of disturbance sensitive species at location C.......................................................................................................................................

(1)(b) (i) In location A, identify the months in which abundance levels are lowest and highest for disturbance

indifferent species.Lowest: .............................................................................................................Highest: ............................................................................................................

(1) (ii) Calculate the difference in the abundance levels for the answers in (b) (i).

Answer: ............................................................................................................(1)

(c) Suggest, giving reasons, which location appears to be least affected by human activity over the experimental period.........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................

(3) (Total 6 marks)Recently, a twenty-one year study was completed in Europe to determine the effectiveness of four different farming methods. Two organic methods, biodynamic and bioorganic, and two conventional methods, one using mineral fertilizer only and one using mineral fertilizer and manure, were all compared. The study considered how these four methods affected the physical, chemical, microbial and faunal (animal life) properties of the soil. In the following radial graph, microbial results are presented relative to the conventional method using mineral fertilizer and manure set at 100%.Definitions:Mycorrhizae are associations between roots and fungi that can help roots absorb water and minerals from the soil better than roots without a fungus partner.Dehydrogenase, protease, phosphatase, and saccharase are enzymes in soil microorganisms which contribute to nutrient recycling.

M y co rrh iz ae

S ac ch a ra se

M ic ro b ia l b io m a ss2 00

1 00

0

P h osp h a ta se

D e h y dro g en ase

P ro te ase

K ey :

b io d y n am ic

b io o rg an ic

c on v e n tio n a lu sin g m in e ra lfe r ti lize r o n ly

c on v e n tio n a lu sin g m in e ra lfe r ti lize r an d

(a) (i) Identify which enzyme appeared to be most affected by the different farming methods............................................................................................................................

(1)(ii) Identify which enzyme appeared to be least affected by the different farming methods.

...........................................................................................................................(1)

(b) List the farming methods from the lowest to the highest in their effect on microbial biomass................................................................................................................................................................................................................................................................................................................................................................................................................

(2) (c) Evaluate the claim that organic farming methods are better for soil properties than conventional methods.

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (2) (Total 6 marks)

Downhill skiing is important economically to the alpine regions of Europe. Ski trails (pistes) are being enlarged, their sloping surfaces are being graded (made smooth with machines) and the use of artificial snow is increasing. Alpine habitats normally range from areas of vegetation with rich species diversity to extreme regions where only a few species can survive. Plant communities are often characterized by their proportions of plant groups.Habitat disturbances can alter species composition, diversity and productivity, which may affect ecosystem functioning and stability.The effects of ski piste preparation on alpine vegetation were studied. The following data shows the differences in species composition between ski pistes and a nearby undisturbed area (the control).

Mea

n di

ffere

nce

in %

cov

erre

lativ

eto

cont

rol

1 0

0

– 1 0

– 2 0

– 3 0

– 4 0

K e y :

u n g rad ed p is tesw ith n a tu ra l sn o w

u n g rad ed p is tesw ith a rtifc ia l sn o w

g rad ed p is te sw ith n a tu ra l sn o w

g rad ed p is te sw ith a rtifc ia l sn o w

G rasses H erb s o th e r Wo o d y p la n ts L eg u m esth a n g ra sse s

P lan t g ro u p s(a) State one reason for the changes shown for ungraded ski pistes with natural snow relative to the control.

..................................................................................................................................... (1)

(b) (i) Identify which type of ski piste preparation caused the least overall impact on vegetation............................................................................................................................

(1)(ii) Identify which plant group is negatively affected by all four types of preparation.

...........................................................................................................................(1)

(c) Analyse the effects of grading ski pistes on alpine vegetation................................................................................................................................................................................................................................................................................................................................................................................................................

(2) (d) It is hypothesized that use of artificial snow (derived from nearby lakes, rivers or ground water) will promote growth

of vegetation.(i) Suggest a reason for this hypothesis.

...........................................................................................................................(1)

(ii) Deduce, giving a reason, whether the data supports this hypothesis.......................................................................................................................................................................................................................................................

(1) (Total 7 marks)The Southern Oscillation Index (SOI) is an indicator of global climate cycle changes. Large negative values indicate warmer than normal weather (El Niño), whereas large positive values suggest colder than normal weather (La Niña).Between 1988 and 1998, scientists studied the effect of changes in the SOI on Dendroica caerulescens, the black-throated blue warbler, a migratory songbird. Each dot in the diagrams represents the mean value calculated for that year.

9 2

9 7

9 3

9 19 4

8 6

9 0

9 89 5

8 8

8 9

9 6

– 1 .5 – 1 .0 – 0 .5 0 .0 0 .5 1 .0

7 .5

8 .0

8 .5

– 1 .5 – 1 .0 – 0 .5 0 .0 0 .5 1 .0

9 2

9 3

9 7

9 4 9 1

9 8

8 6

9 0

9 5

8 9

9 6

8 8

2

3

4

5

S O I / a rb itra ry u n its S O I / a rb itra ry u n its

Mea

n nu

mbe

r of b

irds

able

to le

ave

nest

Mas

s of y

oung

of b

irds

able

to le

ave

nest

/ g

(a) State the average mass of juvenile birds leaving their nest in 1989......................................................................................................................................

(1) (b) Compare the relationship between young birds’ mass and mean number of birds able to leave the nest.

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (2)

(c) Discuss the implications of global climate changes for the warblers................................................................................................................................................................................................................................................................................................................................................................................................................

(3) (Total 6 marks)Fishing activities in marine ecosystems often result in catching unwanted species in addition to the target species. Together with undersize fish, this unwanted catch is often discarded. Discarded fish are a key food resource for many seabird species. The great skua (Stercorarius skua) is a scavenger which feeds on other birds, sand eels and discarded fish.The graph below shows the effect of the size of the sand eel population and the estimated amount of discarded fish on the proportion of birds in the great skua diet.

0 .6 0

0 .5 0

0 .4 0

0 .3 0

0 .2 0

0

1 0 0

2 0 0 2 0 0E s tim a tes o f 1 5 0

d isca rd ed fsh /1 0 k g 3 0 0 1 0 0 S a n d e e l b io m ass

4 0 0 5 0 /1 0 k g0

6

6

P ro p o r tio n o f b ird s inth e g rea t sk u a d ie t

(a) State the relationship between the amount of discarded fish and the proportion of birds in the great skua diet when sand eel biomass is low.......................................................................................................................................

(1) (b) Outline the relationship between sand eel biomass and the proportion of birds in the great skua diet when the

estimated amount of discarded fish is high.............................................................................................................................................................................................................................................................................

(2) (c) Suggest one reason why the amount of discarded fish may decrease in the future.

......................................................................................................................................

......................................................................................................................................(1)

(d) Predict two possible consequences on the ecological community structure if the amount of discarded fish decreases.............................................................................................................................................................................................................................................................................

(2)(Total 6 marks)Methane produced by anaerobic bacteria contributes substantially to atmospheric methane concentration. These bacteria are found in a variety of habitats. Some live inside the cytoplasm of larger unicellular organisms and are known as endosymbionts. In marine sediments, endosymbionts living in the cytoplasm of a group of unicellular organisms, known as ciliates, can contribute up to 90% of methane production.To see if endosymbionts in freshwater sediments had the same effect on methane production a one-year study was carried out in Holland. The graph below shows the rate of methane production by untreated sediment samples and sediment samples treated to kill the ciliates containing endosymbionts. The standard deviations are indicated by bars. The total number of ciliates is also indicated by circles.

k ey : u n trea te d tre a te d

Cili

ate

num

bers

/ m

l sed

imen

t 1 5 0

1 0 0

5 0

0

3

2

1

0

Rat

e of

met

hane

pro

duct

ion

/

mol

met

hane

g

–1 h–1

O N D J F M A M J J A STim e / m o n th s

(a) State what the standard deviation indicates......................................................................................................................................

(1) (b) State the maximum number of ciliates and the month in which the maximum occurs.

.....................................................................................................................................(1)

(c) Compare the methane production in the untreated and treated samples................................................................................................................................................................................................................................................................................................................................................................................................................

(2) (d) Deduce, with reasons, whether the endosymbionts in the ciliates are responsible for the methane produced by the

sediment samples................................................................................................................................................................................................................................................................................................................................................................................................................

(2)(e) Explain how methane and other greenhouse gases cause global warming.

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (2)

Models predict global warming will cause sea temperatures to rise by approximately 2C by 2100. An investigation was carried out to study the effect of slight increases in temperature on the ability of Antarctic marine molluscs to carry out basic activities essential for survival.

The graph below shows the effect of temperature on the percentage of limpets (Nacella concinna) able to right themselves after being turned over.

Tem p era tu re / ºC6543210

2 0

4 0

6 0

8 0

1 00

0

% ri

ghtin

g in

24h

rs

(f) Outline what the two parts of the scientific name Nacella concinna refer to...........................................................................................................................................................................................................................................................................

(1)(g) State the relationship between temperature and the percentage righting in N. concinna.

..................................................................................................................................... (1)

(h) Estimate the percentage change of N. concinna able to right themselves when the temperature is raised from 0C to 2.5C......................................................................................................................................

(1) (i) At present, the maximum summer temperature in the normal Antarctic environment of this organism is 1C. Suggest

what might be the effect on the survival of this organism if the predicted rise in sea temperature due to global warming occurs...........................................................................................................................................................................................................................................................................

(2) (Total 13 marks)The timing of breeding in tree swallows (Tachycineta bicolor) was studied in the United States and Canada from 1959 to 1991. Figure A represents the mean egg laying date for each year. The date is indicated as number of days after January 1st. Figure B shows the correlation between mean May temperature (C) and mean laying date over the same period.

F ig u re A

14 01 9 60M

ean

egg

layi

ng d

ate

(day

of y

ear)

Tim e /y ear

F ig u re B

16 0

15 5

Mea

n eg

g la

ying

dat

e(d

ay o

f yea

r)

M ean M a y tem p era tu re /°C1 9 7 0 19 80 1 9 9 0

14 5

15 0

15 5

16 0

14 0

14 5

15 0

10 12 14 16 1 8

(a) Identify the year with the earliest mean egg laying date......................................................................................................................................

(1) (b) Outline the relationship between mean laying date and mean May temperature.

.....................................................................................................................................(1)

(c) Evaluate the evidence for global warming using figures A and B...........................................................................................................................................................................................................................................................................

(2) (d) A change in mean laying date may increase competition with another species.

(i) State the competitive exclusion principle............................................................................................................................

(1) (ii) Apply the competitive exclusion principle to a change in mean laying date for the tree swallow.

...........................................................................................................................

...........................................................................................................................(2)

(Total 7 marks)

9.1.1 Draw and label plant diagrams to show the distribution of tissues in the stem and leaf of a dicotyledonous plant. Note: Either sunflower, bean or another dicotyledonous plant with similar tissue distribution should be used. Note that plan diagrams show distribution of tissues (for example, xylem, phloem) and do not show individual cells. They are sometimes called “lowpower” diagrams.

9.1.2 Outline three differences between the structures of dicotyledonous and monocotyledonous plants. Note: Teachers should emphasize three differences between monocotyledonous and dicotyledonous plants (examples include: parallel versus net-like venation in leaves, distribution of vascular tissue in stems, number of cotyledons, floral organs in multiples of 3 in monocotyledonous versus 4 or 5 in dicotyledonous, fibrous adventitious roots in monocotyledonous versus tap root with lateral branches in dicotyledonous).

9.1.3 Explain the relationship between the distribution of tissues in the leaf and the functions of these tissues. Note: This should be restricted to dicotyledonous plants. The functions should include: absorption of light, gas exchange, support, water conservation, and the transport of water and products of photosynthesis.

9.1.4 Identify modifications of roots, stems and leaves for different functions: bulbs, stem tubers, storage roots and tendrils.

9.1.5 State that dicotyledonous plants have apical and lateral meristems. Note: Apical meristems are sometimes referred to as primary meristems, and lateral meristems as cambium. Meristems generate new cells for growth of the plant.

9.1.6 Compare growth due to apical and lateral meristems in dicotyledonous plants.

9.1.7 Explain the role of auxin in phototropism as an example of the control of plant growth.

9.2.1 Outline how the root system provides a large surface area for mineral ion and water uptake by means of branching and root hairs.

9.2.2 List ways in which mineral ions in the soil move to the root. Note: There are three processes: diffusion of mineral ions, fungal hyphae (mutualism), and mass flow of water in the soil carrying ions.

9.2.3 Explain the process of mineral ion absorption from the soil into roots by active transport.

9.2.4 State that terrestrial plants support themselves by means of thickened cellulose, cell turgor and lignified xylem.

9.2.5 Define transpiration. Transpiration is the loss of water vapour from the leaves and stems of plants. Aim 7: Data logging with pressure sensors, humidity, light or temperature probes to measure rates of transpiration can be performed.

9.2.6 Explain how water is carried by the transpiration stream, including the structure of xylem vessels, transpiration pull, cohesion, adhesion and evaporation. Note: Limit the structure of xylem vessels to one type of primary xylem.

9.2.7 State that guard cells can regulate transpiration by opening and closing stomata.

9.2.8 State that the plant hormone abscisic acid causes the closing of stomata.

9.2.9 Explain how the abiotic factors light, temperature, wind and humidity, affect the rate of transpiration in a typical terrestrial plant.

9.2.10 Outline four adaptations of xerophytes that help to reduce transpiration. Note: These could include: reduced leaves, rolled leaves, spines, deep roots, thickened waxy cuticle, reduced number of stomata, stomata in pits surrounded by hairs, water storage tissue, low growth form, CAM (crassulacean acid metabolism) and C4 physiology.

9.2.11 Outline the role of phloem in active translocation of sugars (sucrose) and amino acids from source (photosynthetic tissue and storage organs) to sink (fruits, seeds, roots). Note: No detail of the mechanism of translocation or the structure of phloem is required.

9.3.1 Draw and label a diagram showing the structure of a dicotyledonous animal-pollinated flower. Note: Limit the diagram to sepal, petal, anther, filament, stigma, style and ovary.

9.3.2 Distinguish between pollination, fertilization and seed dispersal.

9.3.3 Draw and label a diagram showing the external and internal structure of a named dicotyledonous seed. Note: The named seed should be non-endospermic. The structure in the diagram should be limited to testa, micropyle, embryo root, embryo shoot and cotyledons.

9.3.4 Explain the conditions needed for the germination of a typical seed. Note: Seeds vary in their light requirements and, therefore, this factor need not be included.

9.3.5 Outline the metabolic processes during germination of a starchy seed. Note: Absorption of water precedes the formation of gibberellin in the embryo’s cotyledon. This stimulates the production of amylase, which catalyses the breakdown of starch to maltose. This subsequently diffuses to the embryo for energy release and growth. No further details are expected.

9.3.6 Explain how flowering is controlled in long-day and short-day plants, including the role of phytochrome. Note: Limit this to the conversion of Pr (red absorbing) to Pfr (far-red absorbing) in red or white light, the gradual reversion of Pfr to Pr in darkness, and the action of Pfr as a promoter of flowering in long-day plants and an inhibitor of flowering in short-day plants.