relationship of organisms 270410

8/3/2019 Relationship of Organisms 270410

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Relationship of Organisms

With one another and with the environment


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Learning Objectives (chapter 21)

You should be able to:

State the principal source of energy input to biologicalsystems

Describe the non-cyclical nature of energy flow Establish the relationship of the following in food webs:

producer; consumer; herbivore; carnivore; decomposer;food chain

Describe the energy losses between trophic levels and

infer the advantages of short food chains. Describe the importance of the carbon cycle.*


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Lesson Objectives (chapter 22)

Describe the effects of Man on the ecosystem with emphasis

on examples of international importance (tropical rainforests,

oceans, important rivers)

Evaluate the effects of:

Water pollution by sewage and by inorganic waste Air pollution by sulphur dioxide and oxides of nitrogen (acid rain)

Pollution due to insecticides

Discuss reasons for conservation of species with reference to

maintenance of biodiversity, management of fisheries AND

management of timber production

Discuss reasons for the recycling of materials with reference

to named examples


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Newsflash!!

Malaria once infected nine out of ten people in Brunei Darussalam. In 1955, theWorld Health Organisation (WHO) began spraying the insecticide dieldrin to kill the

malaria-carrying mosquitoes. The program was so successful that the dreaded

disease was almost eliminated. Then strange things started to happen

The dieldrin killed other insects, including flies and cockroaches, living in the

houses. Then the geckos which lived in the houses died after eating the dead

insects. Then cats began dying after eating the dead lizards. Without cats, the ratsflourished. With the rats came the plague, carried by fleas on the rats. The situation

was only brought under control when WHO parachuted healthy cats onto Brunei.

The roofs of the houses began to fall in. The dieldrin had killed wasps and other

insects that fed on a type of caterpillar that either avoided or was not affected by

the insecticide. With most of its predators eliminated, the caterpillar population

grew rapidly. The caterpillars ate their favourite foods, the leaves used to thatch theroofs of the houses.

Eventually, the numbers of predatory insects recovered and the spraying

programme was a success story. But it does show the unpredictable results that

can happen when humans interfere with ecosystems.


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Activity Time!

Can you list the various ways in which the organisms in the newsreport interacted with each other?

Flies &

cockroaches

Geckos Cats Rats

Wasps & other

insectsCaterpillars

LeavesFleas

Malaria-carrying

MosquitoesHumans


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Answers:

Flies &

cockroachesGeckos

Cats

Rats

Wasps & other

insects

Caterpillars Leaves

Fleas

Malaria carrying-Mosquitoes Human blood


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What is Ecology? Ecology is the study of interactions

among organisms, and between

organisms and the physical and chemical

factors making up their external

environment.

The natural environment is made up of abiotic and biotic factors found in

its surroundings that affect it:

Abiotic factors:

Non-living factors which make up the physical environment

Determines the type of living organisms found in the habitat

Biotic factors:

all the living organisms which an organism interacts with in its

habitat.


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Ecological Terms

A place where an organism lives.

A group of individuals of the same species occupying a given area.

Consists of populations of plants and animals living together and

interacting with one another under the same environmental conditions.

Formed by the interactions of communities and their physical environment.

The function of an organism or the role it plays in the habitat.


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Abiotic/Physical

Environment

Biotic

1. Light

2. Temperature

3. Water

4. Oxygen

5. Salinity (Salt Concentration]

6. Acidity/alkalinity (pH)

RelationshipsRelationships

Interdependence between

various populations in any

community


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Light intensity

Green plants exist only where is an adequatesupply of sunlight.

It affects the distribution and growth of plants and

animals.

Adaptation of PLANTS to light intensity:

In areas where light penetration is poor,

Trees grow taller

Some plants make use of tall trees to reach

sunlight, e.g. climbers

Too much of sunlight, Retards elongation of stem

Dense covering of hairs on leaf epidermis to

screen off excess light and heat

a layer of thick-walled cells known as hypodermis

found beneath the epidermis


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Light intensity

Animals need light in order to

see, move, find food and detect danger.

Bats hanging in a

cave

Special adaptations:In areas like caves where there is a

lack of light,

Bats have a highly sophisticated

sense of hearing

By emitting sounds that bounce off

the objects in their path, which send

echoes back to the bats.

Bats detect the echoes and are able

to determine the size and distance of

the objects.


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TemperatureTemperature affects the physiological activities of plants and animals.

For many flowering plants,

These are some adaptive features to survive the seasonal changes:

The shedding of leaves to reduce water loss

Formation of seeds that are resistant to drought, heatand cold so that they are able to survive the

unfavourable seasons

Underground storage organs

Temperature affects also the metabolic activities of

the organisms because it indirectly affects rate of

enzyme action on a substrate.


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During winter, polar bears curl up in temporary

caves or find natural shelter to keep warm.

They hibernate and live off their stored body

fats which were accumulated when food was

plentiful.

Temperature

More examples

How do penguins survive the cold?

Thick layers of fat help to insulate

them from the cold.Feathers help to trap air which is a

poor conductor of heat.


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Cacti

thick waxy cuticle

leaves reduced to spines

few stomata

fleshy stems to store water

green stems which take over function

of photosynthesis from leaves

Water Essential for life.

Must be present in the environment of every organism.

Medium for aquatic plants and animals

Availability of water depends on the distribution of rainfall in a year.

What are Xerophytes?

Plants which can live in conditions of prolonged

drought in their habitat.

Examples: Cactus, Casuarina, marram grass, etc.

To reduce rate of

transpiration/ waterloss from leaf surface


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Adaptations of plants to dry habitats

In marram grass:

Rolled up leaf to reduce surface area

exposed to surrounding.

Deeply grooved inner leaf surface with

stomata

Spines/hairs to trap water vapour

diffusing out of stomata.

Increase humidity around the stomata

Reduces the rate of transpiration

For the plant Casuarina,

The leaves are reduce to tiny sheaths

at the stem nodes

Long green stems have stomata that liein grooves protected by minute hairs

Leaves

Stem


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WaterWhat are Hydrophytes?

Plants which live in water or very wet places.Examples of hydrophytes:

Hydrilla (completely submerged)

Water lily (partially submerged)

Water hyacinth (free floating)

Adaptive features to wet habitat:

Large surface area of leaf for

photosynthesis

Air spaces in leaf to help the plant

float on water.

Vascular bundle poorly developed

as water enters the plants cell directly

Upper surface of leaf protected by

waterproof cuticle to prevent water

from blocking the stomata


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Water

Mangrove plants such as Avicennia, have roots

buriedin oxygen-poormud.

Adaptations:

special breathing roots calledpneumatophores arise from root system out of

the mud surface.

Has openings/pores which allow oxygen to

pass downwards to the root system.


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Adaptations of animals to dry habitats.

CamelsAdaptive features:

Able to survive without

water for weeks

Humps store fats whichcan be broken down to

provide energy and

metabolic water during

respiration.


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Oxygen Required forrespiration

What is the difference between

Land animals and plants vs. aquatic animals and plants

Oxygen from air (Land)

Oxygen dissolved in water (Aquatic)

Exceptions? For example: Mudskipper.

Lives in water but is able

to obtain oxygen from air.


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Marine aquarium

(similar to sea environment)

Higher salt content

Salinity (salt concentration)

Important factor for aquatic organisms

Freshwater aquarium

(similar to pond environment)

Lower salt content

Freshwater plants have rigid cellulose cell

walls to prevent from bursting.

Protozoa such as Amoeba have contractile

vacuoles to remove excess water entering by

osmosis.


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Kidney and accessory organs play a role in maintaining constant internal

environment. But how do they do it?

Salinity

Other adaptations:

Saltwater fish have waterproofcoat which consists of:

Closely fitting scales

Slimy mucous material

Freshwater fish:

Excessive water entering body cells

by osmosis Salt loss from body cells by diffusion

Marine Fish

Water loss from body cells

Salt moving into body cells from

sea environment.

Freshwater fish: Kidney reabsorbs salts and produces

large amounts of dilute urine

Cells in gills uptake salt from water

Marine Fish:

excretes salts and small amounts ofwater, producing highly concentrated

urine

Cells in gills secrete salt into

surroundings


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pH (acidity/alkalinity)

pH value of water in soil, ponds or sea affects the kind of

organisms that live in these habitats. Affects the enzymatic activity of the cells in the organisms.

For example, pineapples and cotton plants grow best in acidic soil


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pH (acidity/alkalinity)

Sea water Slightly alkaline (pH~8)

Remains more or less constant

Freshwater pH varies from one region to another

Dependent on bicarbonate ions present in the water.

In the day, photosynthetic activity of the plants use upcarbon dioxide in the water making if more alkaline.

At night, no photosynthesis takes place, aquatic plantsrespire producing carbon dioxide which is dissolved inwater, making water more acidic.


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The EcosystemThe Earth is one giant ecosystem with all living things interacting with the

environment and each other, using and reusing the finite resources to live.

It is a self supporting unit with the following components:

A constant source of energy SUNLIGHT

Food producers

Food consumers

Decomposers

http://www.open2.net/diyscience/ecosphere/index.html

An ecosystem requires both energy and

material (inorganic nutrients) to sustain itself.

Energy enters an ecosystem from outside

and flows through in a non-cyclic manner.

Materials are obtained from physical

environment and flow through the

ecosystem in a cyclic manner.


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Energy flow:

Sun PlantsAnimals Decomposers

Trapped by

chlorophyll

Plant dies

Animal dies

Eaten by

Light energyChemical energy

Chemical energy

Ecosystem

One-way flow of energy in an ecosystem

Heat energy Heat energy Heat energy

Chemical energy


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Non-cyclical nature of energy flow

When plants trap suns energy and pass it on to the

other living organisms

Only 1% of sunlight enters the ecosystem which is trapped

by plants All the energy is eventually lost to the non-living

environment as heat energy Heat is considered a waste energy as organism cannot use it

Heat cannot reenter the ecosystem Energy flow is thus one way (non-cyclical) as it is not recycled.


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Understanding Food chains and food webs

Organisms in an ecosystem can be grouped according to their functions

Organisms Functions

Producers Mainly green plants that manufacture complex organicfood substances from simple inorganic raw materials

via photosynthesis

Consumers

Primary Consumers

Secondary/Tertiary

Consumers

Organisms that obtain energy from other organisms onwhich they feed.

a) Herbivores Feed directly on plants

b) Carnivores Feed on other organisms

c) Scavengers Feed on dead/decaying organisms

d) Parasites Feed on living tissues of organisms


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Understanding Food chain and webs

Organisms Functions

Decomposers Feed on dead organisms

Breakdown complex nutrients locked up in them

into simple inorganic substances which are returned

to the non-living environment to be reused.

Examples of decomposers are fungi

and bacteria


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Food chain A series of organisms

through which energy is

transferred in material

form (food) constitutes

a food chain.

Each stage in the food

chain is a trophic level.

Trophiclevel 1

Trophiclevel 2

Trophiclevel 3

Trophiclevel 4

Trophiclevel 5


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Food webs A complex feeding

relationship within acommunity where two ormore food chains arelinked by eating differenttypes of plants and animals,

a consumer has a betterchance of survival.

If one food sources are

destroyed, other food sourcesare available


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Ecological Pyramids Pyramid of energy

Represents the rate of energy flow in a food chain

Always upright ( i.e. broad base tapering to narrow apex) Shows that amount of stored energy gets smaller at each tropic level.

Energy transfer:

Only 10% of chemical energy

is converted into new tissueand made available for the next

link in the food chain.

- Energy is almost completely

dissipated into surroundingsby the 4th or 5th trophic level.


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Ecological Pyramids

Pyramid of numbers

Can you name some other

organisms that could be used for

each of the levels in the diagram

below?


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Ecological pyramids Pyramid of biomass

Since the amount of water present within the tissues of different organismsvaries, biologists use the dry mass of the organism for comparison since it is

believed that dry mass more closely reflects the actual amount of"living

matter" in the organism. The dry mass is known as biomass.

In a grassland environment, 10,000 kg of grass and other producers (dry mass)

should support about 1,000 kg (dry mass) of grasshopper and other plant eatinginsects.


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Ponder this!What are the advantages of having a shorter food chain?

Reduce the amount of energy lost through trophic levels

More energy is available at the beginning of the food chain

It seems like

It is more efficient to eat green plants for food

Less efficient if crops are fed to cattle and then consumed when manfeed on cattle.

But why dont we all become vegetarians instead? Man is unable to digest cellulose

Cattle can turn energy in cellulose into energy in protein and fat. (this

can be digested by man) Selection of crops:

Important to feed on crops which man can digest directly e.g. soyaproducts which are high in protein.

relationship of organisms 270410

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