f215 module 3 chapter 1

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F215 - Module 3 chapter 1 - Ecosystems

a. Define the term ecosystems

·         Ecosystems is where all of the living organisms and non-living components in a specific habitat and their interactions.

b. State that ecosystems are dynamic systems

·         They are dynamic systems because the population rises and falls due to the interactions of living organisms between each other and with the physical environment.

c. Define the terms biotic factor and abiotic factor using named examples

·         Biotic factor:

These are factors due to living organisms.

E.g. food supply, predation, disease.

·         Abiotic factor:

The factors and effects of the non-living components.

E.g. pH of the soil, temperature and soil type.

d. Define the terms producer, consumer, decomposer and tropic levels

·         Producer: These are the autotrophic organisms such as plants, some protoctists and some bacteria that convert light energy to chemical energy which is then supplied to consumers.

·         Consumer: Living organisms that feed on other living organisms.

·         Decomposer:  Organisms that feed on dead organic material releasing molecules, minerals and energy for other living organisms in that ecosystem to use.

·         Trophic levels: these are the level at which an organism feed in a food chain.

e. Describe how energy is transferred by ecosystems

·         Producer to Primary consumer to Secondary consumer to Tertiary consumer

·         Food webs show the transfer of energy by showing which way the energy flows.

f. Outline how energy transfers between trophic levels can be measured

·         Pyramids of biomass:

Area of bars are proportional to the dry mass of all the organisms at that trophic level.

·         Pyramids of energy:

Burning the organisms in a calorimeter and work out how much heat energy is released per gram by calculating it from the temperature rise of a known mass of water.

·         Productivity:

The rate of energy flow passing through each trophic level.

Gross primary productivity-The rate at which plants convert light energy into chemical energy.

Net primary productivity-The energy available to the primary consumer. It is gross primary productivity-the energy lost when the plant respires.

g. Discuss the efficiency of energy transfer between trophic levels

·         At each trophic level some energy is lost from the food chain.

Because of living organisms needing energy to carry out life processes.

Loss via heat energy.

Energy remains stored in dead organisms and waste material which can only be accessed by decomposers.

Not all of the plant/animal may


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