Biology 12

Term 1Revision

Module 0Grasses form a major part of agricultural pastures around the world, in drier parts of the world these

grasses are annuals, meaning that they complete their life cycle in one season, produce seed and die. The seeds germinate in wet seasons of following years to renew the pasture. Some seeds germinate the very next year but others remain dormant for up to several years before germinating.

A scientist investigated the dormancy rates for seeds of three different species of annual grass. Two grams (2 g) of seed of each species were planted in separate square metre plots. No other plant species was present in the plots. Each year for six years the number of seeds that germinated in each plot was counted. The seedlings were then removed so that no new seeds were produced in the plots. The results of this experiment are shown in the table below.

a) What hypothesis might he be testing?b) Identify the dependent variable.c) Identify the independent variable

Grass species

Time elapsed (years)

1 2 3 4 5 6

Number of seeds

germinated (No per m2)

A 610 320 No reading 140 20 5

B 415 35 0 0 0 0

C 380 100 35 15 10 No reading

Module 0Grasses form a major part of agricultural pastures around the world, in drier parts of the world these

grasses are annuals, meaning that they complete their life cycle in one season, produce seed and die. The seeds germinate in wet seasons of following years to renew the pasture. Some seeds germinate the very next year but others remain dormant for up to several years before germinating.

A scientist investigated the dormancy rates for seeds of three different species of annual grass. Two grams (2 g) of seed of each species were planted in separate square metre plots. No other plant species was present in the plots. Each year for six years the number of seeds that germinated in each plot was counted. The seedlings were then removed so that no new seeds were produced in the plots. The results of this experiment are shown in the table below.

a) What hypothesis might he be testing? Different grass species have different seed survival rates

b) Identify the dependent variable. Germination ratec) Identify the independent variable. Grass species

Grass species

Time elapsed (years)

1 2 3 4 5 6

Number of seeds

germinated (No per m2)

A 610 320 No reading 140 20 5

B 415 35 0 0 0 0

C 380 100 35 15 10 No reading

Module 0Grass

speciesTime elapsed (years)

1 2 3 4 5 6

Number of seeds

germinated (No per m2)

A 610 320 No reading

140

20 5

B 415 35 0 0 0 0

C 380 100 35 15 10 No reading

Graph this data

For species A in year 3 and species C in year 6 valid measurements were not taken because of unexpected interference with the plots.

Use the graph that you have drawn to predict likely values for these readings had it been possible to measure them.

(i) Species A year 3(ii) Species C year 6 In which prediction do you have

greatest confidence? Explain why.

Module 0Grass

speciesTime elapsed (years)

1 2 3 4 5 6

Number of seeds

germinated (No per m2)

A 610 320 No reading

140 20 5

B 415 35 0 0 0 0

C 380 100 35 15 10 No readin

g

Graph this data

For species A in year 3 and species C in year 6 valid measurements were not taken because of unexpected interference with the plots.

Use the graph that you have drawn to predict likely values for these readings had it been possible to measure them.

(i) Species A year 3 210(ii) Species C year 6 0 - 5In which prediction do you have greatest

confidence? Explain why. i) – it is within the plotted points

time

germination

1 2 3 4 5 6

200

100

300

400

500

600

700

Graphing question

Grass species

Time elapsed (years)

1 2 3 4 5 6

Number of seeds

germinated (No per m2)

A 610 320 No reading 140 20 5

B 415 35 0 0 0 0

C 380 100 35 15 10 No reading

All plots were planted with equal amounts of seed (2 g per m2), yet very different numbers of plants grew in each plot.

Give two possible reasons to explain this

Grass seeds germinate when it rains but fail to mature if there is not enough rainfall, dying before they produce seed. In the year following a severe year of drought, pasture growth depends largely on dormant seeds in the soil that are least two years old.

In a period of extended drought (two or more years) which of the three species of grass would suffer the greatest reduction?

Give an explanation for your answer above

Graphing question

All plots were planted with equal amounts of seed (2 g per m2), yet very different numbers of plants grew in each plot.

Give two possible reasons to explain thisViability rate differed between plots, so some seeds did not germinate The size of the seeds differed between plots, so there was less seed in some plots (seeds were allocated

by weight)Seed dormancy may limit initial germination, so not all seed germinated in both plotsSome species better adapted to the conditions, so germinated more readilySeed of different species may be of different ages, so differed in viability Some species may be more palatable, so more heavily predated

Grass seeds germinate when it rains but fail to mature if there is not enough rainfall, dying before they produce seed. In the year following a severe year of drought, pasture growth depends largely on dormant seeds in the soil that are least two years old.

In a period of extended drought (two or more years) which of the three species of grass would suffer the greatest reduction? Species B

Give an explanation for your answer aboveSpecies B’s germination declines to 0 after 2-3 years, therefore no seeds left/ to regenerate species

Grass species

Time elapsed (years)

1 2 3 4 5 6

Number of seeds germinated (No per m2)

A 610 320 No reading

140 20 5

B 415 35 0 0 0 0

C 380 100 35 15 10 No reading

Multiple choice 1

The above diagrams represent cells after one hour in solutions of different concentrations of salt

The concentration of salt in which pair of cells is greater than the concentration of salt in their environment? (a) I and IV (b) IV and VI (c) III and V (d) II and VI

Multiple choice 1

The above diagrams represent cells after one hour in solutions of different concentrations of salt

The concentration of salt in which pair of cells is greater than the concentration of salt in their environment? (a) I and IV (b) IV and VI (c) III and V (d) II and VI

Multiple choice 2

A student used a microscope to observe a stomate on a leaf epidermis. With a 10x ocular lens and a 20x objective lens the following view was seen through the microscope.

If the stomate, including the guard cells, is known to be 50 m wide, which of the following is the closest estimate of the field diameter? (a) 0.25 mm (b) 0.5 mm (c) 1.5 mm (d) 2.5 mm

Multiple choice 2

A student used a microscope to observe a stomate on a leaf epidermis. With a 10x ocular lens and a 20x objective lens the following view was seen through the microscope.

If the stomate, including the guard cells, is known to be 50 m wide, which of the following is the closest estimate of the field diameter? (a) 0.25 mm (b) 0.5 mm (c) 1.5 mm (d) 2.5 mm

Multiple choice 3

The student altered the lens combination of the microscope and observed the following view of the same section of the same slide.

Which new lens combination would be most likely to provide this view? (a) A 15x ocular and a 40x objective. (b) A 10x ocular and a 30x objective. (c) A 10x ocular and a 40x objective. (d) A 20x ocular and a 25x objective.

10x ocular lens 20x objective lens

Multiple choice 3

The student altered the lens combination of the microscope and observed the following view of the same section of the same slide.

Which new lens combination would be most likely to provide this view? (a) A 15x ocular and a 40x objective. (b) A 10x ocular and a 30x objective. (c) A 10x ocular and a 40x objective. (d) A 20x ocular and a 25x objective.

10x ocular lens 20x objective lens

Label the cells

Label the cellsCell wall

Cell membrane Cell

membrane

Mitochondrion

Mitochondrion

Vacuole Vacuole

CytoplasmCytoplasm

NucleusNucleus

Nucleolus NucleolusNuclear membrane Nuclear

membraneDNA

DNA

Golgi bodyGolgi body

Centrioles

Chloroplast

ER & ribosomes ER & ribosomes

What type of cell am I?

What type of cell am I?animal

animal

plant

plant

Organelles 1

• cell membrane • cell wall • cytoplasm• nucleus• nucleolus• nuclear membrane• mitochondria• Golgi body

• Packages for secretion• Controls cell metabolism• Aerobic respiration• RNA synthesis & storage• Controls entry & exit from

cell• Medium for reactions• Provides structure &

support for cell• Protects DNA

Organelles 1• Packages for secretion - Golgi body• Controls cell metabolism - nucleus• Aerobic respiration - mitochondria• RNA synthesis & storage - nucleolus• Controls entry & exit from cell - cell membrane • Medium for reactions - cytoplasm• Provides structure & support for cell - cell wall • Protects DNA - nuclear membrane

Organelles 2• endoplasmic reticulum • ribosomes• lysosomes• centrioles• cilia/flagella• chloroplasts• vacuole• contractile vacuole

• Protein synthesis• Water removal • Makes spindle• Movement• Photosynthesis• Waste storage and

removal• Storage• Transport

Organelles 2• Protein synthesis - ribosomes• Water removal - contractile vacuole• Makes spindle - centrioles• Movement - cilia/flagella• Photosynthesis - chloroplasts• Waste storage and removal - lysosomes• Storage - vacuole• Transport - endoplasmic reticulum