Biology Fom 4

8/6/2019 Biology Fom 4

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Chapter 8 :

ecology

BIOLOGY


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ECOLOGY

Is the scientific study of theinteractions of living organisms and

with the physical environment. They cannot exist as separate

entity.

Instead,they are interrelated andform a complex system.


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THE ABIOTIC AND

BIOTIC COMPONENTS

OF THE ENVIRONMENT


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THE ABIOTIC COMPONENT

(NON-LIVING ORGANISMS)Abiotic component determine the population size andAbiotic component determine the population size and

distribution of the biotic component.distribution of the biotic component.

Abiotic component consist of ;Abiotic component consist of ;

The pH valueThe pH value

Light intensityLight intensity

TemperatureTemperature

HumidityHumidity

TopographyTopography

microclimatemicroclimate


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The pH value The pH value of the soil and water has a significant

effect on the distribution of organisms that live in a

habitat.

Aquatic organisms are sensitive to the effects of the

pH of water and may be killed if the changes pH areconsiderable.

Light intensity

The varying intensities of sunlight in a forest result inthe growth of different types of plants.


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Example;

Tall trees form the canopy

Plants such as ferns and vines

Birds,bats and tree frogs

Mosses and animals such as ants andearthworms thriye

Bacteria and fungi decompose organic material

High

intensity

of

sunlight

Low

intensity

of sunlight


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Temperature Most living organisms survive within the temperature

range of 0C-45C.

A drop in a temperature within a certain range usually

results in a decrease in the metabolic activities of

organisms. Temperature higher than 45C usually cause enzymes

to be denatured.however,there are some species of

organisms that can live under extreme

temperatures.exp; thermophilic bacteria.

Aquatic environment undergo less extreme

temperature changes and therefore provide more

stable habitats than terrestrial environment.


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Humidity

Is the effects the rate of water loss by plants andanimals.

When humidity ,water evaporates from the moist

surfaces at faster rate.

Humidity is usually at night but during the day.

Some organisms regulate their activities to prevent

dehydration.

Exp; woodlice are usually found under stones androtting tree stumps.


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Topography Is the physical features of the land which concern the

altitude,gradient and aspect of a region.

Altitude;

A altitude is associated with a atmospheric andtemperature.

Thus, different plants grow at different altitude.

Gradient;

Steep slopes result in rapid drainage & run-off.

Therefore,the soil layer is thinner & dried.Hence, this

area is not a suitable habitat for organisms.


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Aspect;

The slope of mountains facing the direction of wind

receive more rain than the slopes shaded from the

wind.

Thus,the organisms from different slopes of a

mountain are different. In nothern hemisphere,the slopes facing south

receive more sunlight than the valleys & slopes

facing north.

Hence,this will influence the natural vegetation andland-use by human.


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Microclimate Refers to the climate in a microhabitat.microhabitat.

It includes the humidity,temperature,light intensity

and atmospheric conditions in which the organisms

lives. It also influence the number and distribution of

organisms.


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TTHE BIOTIC COMPONENTHE BIOTIC COMPONENT

(LIVING ORGANISMS)(LIVING ORGANISMS)

Consist of;Consist of;

ProducersProducers

ConsumersConsumers

decomposersdecomposers


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Food chain,food web and

trophic levels A food chain shows a sequence of organisms through whichA food chain shows a sequence of organisms through which

energy is transferred.energy is transferred.

Each stage in a food chain is known as a TROPHIC LEVEL.Each stage in a food chain is known as a TROPHIC LEVEL.

Producers occupy the first trophic level while primaryProducers occupy the first trophic level while primary

consumers occupy the second trophic levelconsumers occupy the second trophic level

the food chains in an ecosystem are usually interconnected tothe food chains in an ecosystem are usually interconnected to

form a FOOD WEB.form a FOOD WEB.

Grass

(producers)

Grasshopers

(primary con.)

Frogs

(secondary con.)

Snakes

(tertiary

consumers)


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In a food web,the source of energy is sunlight.green plants

convert solar energy into chemical energy which is stored infood during photosynthesis.

When a primary consumer feeds on the producers,some of

the energy stored in the plants is passed on to the primary

consumers,which later passes it energy to the secondary

consumers.

In this way,energy flows through a food web.

However,not all the energy is transferred to the next trophic

level in a food web.

Some is lost as heat.


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Energy flow in a food web and the pyramid of numbers

Tertiary

consumers

Secondary

consumers

Primary consumers

producers

ENERGY LOST


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