Click4Biology: 5.1 Communities & ecosystems

Communities and ecosystems

5.1.1 Definitions.

5.1.2 Autotrophs and heterotrophs.

5.1.3 Consumers, detritivores and saprophytes.

5.1.4 Food chains.

5.1.5 Food webs.

5.1.6 Trophic level.

5.1.7 Determining trophic levels in food chains and food webs.

5.1.8 Constructing a food web.

5.1.9 Light and food chains.

5.1.10 Energy flow in a food chain.

5.1.11 Efficiency of energy transformations.

5.1.12 Shape of energy pyramids.

5.1.13 Energy and matter in ecosystems.

5.1.14 Decomposers.

5.1.1 Define species, habitat, population, community, ecosystem and ecology.(1)

Define means to give the precise meaning of a word, phrase or physical quantity.

 

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5.1.2 Distinguish between autotroph and heterotroph.(2)

Distinguish means to give the differences between two or more different items.

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5.1.3 Distinguish between consumers, detritivores and saprotrophs.(2)

Distinguish means to give the differences between two or more different items.

 

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5.1.4 Describe what is meant by a food chain, giving three examples, each with at least three linkages (four organisms).(2)

Describe means to give a detailed account.

Carrot plant ---> Carrot fly ---> Flycatcher -----> Sparrow hawk

1. The carrot fly consumes the carrot plant.

2. Some of the carrot plant molecules are assimilated by the fly for growth of the carrot fly and others are metabolised in fly respiration.

3. The carrot fly is consumed by the flycatcher.

4. Some of the molecules of the carrot fly are assimilated by the fly for growth of the flycatcher and others are metabolised in flycatcher respiration.

5. In turn the flycatcher is consumed by the sparrow hawk.

6. Some of the molecules of the flycatcher are assimilated for the growth of the sparrow hawk and others are metabolised in hawk respiration.

Bushgrass---> Impala ---> Cheetah----> Lion

 

buckwheat ---> Gopher ---> Gopher snake ----> Red Tailed Kite

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5.1.5 Describe what is meant by a food web.(2).

Describe means to give a detailed account.

The food web is a diagram that shows how food chains are linked together into more complex feeding relationships

The food web has a number of advantages over a food chains including:

There are certain problems in drawing a complete food web as this would in most cases require a very complex study and identification of species. For this reason, food webs often reflect the interests of its author. The author will detail the species of interest by name but group other less interesting/ important species into larger family. order groups.

 

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5.1.6 Define trophic level. (1)

Define means to give the precise meaning of a word, phrase or physical quantity.

The trophic level of an organism defines the feeding relationship of that organism to other organisms in a food.

In a food web a consumer can occupy a number of different trophic levels depending on which organism is the prey.

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5.1.7 Deduce the trophic level of organisms in a food chain and a food web.(3)

Deduce means to reach a conclusion from the information given.

 

 

 

 

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5.1.8 Construct a food web containing up to 10 organisms, using appropriate information.(3)


Constructing a foodweb scroll down the page and click the image 'Create a foodweb.

 

5.1.9 State that light is the initial energy source for almost all communities.(1)

State means to give the precise meaning of a word, phrase or physical quantity.

There are other energy sources for deep ocean communities based on geothermal energy. These are not studied on this course but can be read about on this external link

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5.1.10 Explain the energy flow in a food chain.(3).

Explain means to give a detailed account of causes, reasons or mechanisms.

 

a) Not all solar energy will come into contact with chlorophyll and will therefore not be trapped in the synthesis of organic compounds during photosynthesis

b) Photosynthesis in which light energy is trapped by producers.

c) Consumers feeding and passing on energy in the food molecules.

d) Loss of energy as heat from respiration

e) death and the consumption of dead organisms by detritivores. Or as food not assimilated because of incomplete digestion.

Energy Loss

 

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5.1.11 State that energy transformations are never 100% efficient.(1)

State means to a specific name, value or other brief answer without explanation or calculation.

 

 

 

 

5.1.12 Explain reasons for the shape of pyramids of energy.(3).

Explain means to give a detailed account of causes, reasons or mechanisms.

 

 

 

 

 

 

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5.1.13 Explain that energy enters and leaves ecosystems, but nutrients must be recycled.(3)

Explain means to give a detailed account of causes, reasons or mechanisms.

(a) Energy flows: this diagram is a simple version of the pyramids of energy. At each trophic level energy is lost as heat. At the top of the pyramid of energy it tapers to a point showing how all energy is ultimately radiated to space as heat.

(b) Matter cycles: new matter is not created, no new carbon, hydrogen or oxygen. Producers (autotrophs) take inorganic molecules and convert them to organic compounds. Consumers feed at different trophic levels taking in organic matter and using it for their own growth. This cycling of matter is the subject of the carbon, nitrogen and water cycle.

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5.1.14 State that saprotrophic bacteria and fungi (decomposers) recycle nutrients.(1)

State means to give a specific name, value or other brief answer without explanation or calculation.

Saprotrophic bacteria and fungi recycle the nutrient (organic molecules) of dead organisms.

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