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Question 1
The diagram below shows a food chain comprising corn, mice and falcons. |
a) | The corn is a producer. What is meant by the term producer?
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b) | What is the source of energy for the food chain?
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c) | Some of the mouse biomass does not become part of the falcon biomass. Which of the following is a valid reason for this loss of biomass? A some of the mouse is used for the falcon to grow B the falcon produces waste in faeces C the corn is eaten by the falcon
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Question 2
A new pet food brand is selling insect-based cat food. The insects in the cat food factory are fed on waste vegetables. |
a) | Sketch and label the pyramid of biomass for the food chain that produces food for cats from insects.
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b) | Which of the following words correctly describes the vegetables' position in the food chain? A herbivore B primary consumer C producer D prey
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c) | Which of the following words correctly describes the insects' position in the food chain? A carnivore B primary consumer C producer D predator
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d) | Which of the following words correctly describes the cats' position in the food chain? A herbivore B primary consumer C producer D secondary consumer
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e) | Give two reasons why the biomass of the insects eaten by cats does not all become biomass of the cats.
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Question 3
Humans are omnivores. This means humans are organisms that eat plants and animals. The table shows the energy available to humans from two different food chains. |
a) | Compare the amount of energy the two food chains transfer to humans.
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b) | Give two reasons for the difference in the amount of energy transferred to humans by the two food chains.
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Question 4
A food web contains several food chains. The image below shows a food web. |
a) | The animals in the food web above get their energy by eating other organisms. Describe how the grass gets energy.
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b) | Name one primary consumer in food web above.
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c) | Name one producer in the food web above.
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d) | The different food chains in this food web have different numbers of organisms. Write a food chain with four organisms, including the fox.
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e) | The food web shows that weasels eat voles and rabbits. The biomass of weasels is much less than the combined biomass of voles and rabbits. One reason for this is that the weasel cannot digest all parts of the voles and rabbits. Give two more reasons.
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Question 5
Food chains illustrate the passage of food (or energy) from one organism to another. |
The diagram below shows a typical freshwater food chain. algae → stickleback → trout → osprey |
a) | Name the process carried out by the algae that allows energy to enter the food chain.
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b) | Name the secondary consumer in the food chain above.
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c) | In food chains, biomass is lost between different trophic levels. One reason for this is the release of undigested food from the body. What is the release of undigested food called? A decomposition B egestion C decay D diffusion
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d) | Insecticides are often sprayed onto crops to kill insects. Insecticides can be washed off the crops by rain and flow into rivers where they accumulate in food chains. A typical freshwater food chain and the concentration of insecticide in each organism is shown below. |
Calculate the percentage increase in insecticide concentration between the trout and osprey.
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e) | Name and describe the process by which toxins build up in a food chain.
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Question 6
The diagram below shows a pyramid of energy for a typical food chain. |
a) | Explain why a pyramid of biomass always has this shape.
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b) | Only 5% of light energy landing on an oak tree is absorbed by leaves. This is converted to chemical energy. Calculate the total light energy landing on the leaves if they contain 20,000 units of chemical energy.
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c) | The shrews are consumers. Give another ecological term that describes the role of the shrews in this food chain.
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The table below shows what happens to each 20 J of energy gained by the caterpillar from food. |
d) | Which percentage of the energy gained from food is used for heat and movement?
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e) | Which one of these processes allows energy to be passed on to the next level in a food chain? A heat and movement B growth C faeces
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Question 7
The diagram below shows a food web. |
a) | State the number of primary consumers in this food web.
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b) | State the number of food chains in this food web.
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c) | The mountain lion catches and eats its prey. Give the name used to describe the lion in this food web.
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d) | A pesticide can be used to kill the grasshoppers in this habitat. Describe the effect that killing grasshoppers would have on:
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Question 8
A gardener investigated the populations of organisms in her garden. The figure below shows estimates of the number and biomass of some of the organisms she studied. |
a) | Calculate the biomass of the population of earthworms.
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b) | Calculate the mean biomass of each snail.
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c) | Snails eat lettuce and earthworms. The gardener used a pesticide that killed most of the earthworms in the garden. Predict how this will affect the population of lettuces.
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d) | Describe a method that could be used to estimate the percentage change in the population of earthworms in the garden.
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Question 9
Pyramids of biomass show the relative amount of biomass in each level of a food chain. |
a) | Sketch a pyramid of biomass for the following food chain. Grass ➔ Zebra ➔ Lion 80 kg 40 kg 10 kg
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b) | Use the biomass values to suggest why there is usually a maximum of four to five levels in a food chain.
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c) | Explain how respiration reduces the amount of biomass available to the next trophic level in a food chain.
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