7.1 Communities and interdependence
6 exam questions worth 12 marks. Write your answer, open the mark scheme, then give yourself the marks you earned. Your answers are saved on this device.
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Define community and ecosystem.
Mark scheme
- community: populations of different species living in a habitat (1)
- ecosystem: community interacting with the non-living / abiotic parts of the environment (1)
Model answer
A community is all the populations of different species in a habitat. An ecosystem is the community interacting with the non-living parts of its environment.
Give two things plants compete for and two things animals compete for.
Mark scheme
- plants, any two from: light, space, water, mineral ions (2)
- animals, any two from: food, mates, territory (2)
Model answer
Plants compete for light and water; animals compete for food and mates.
What is meant by interdependence?
Mark scheme
species depend on each other (for food, shelter, pollination, etc.)
Model answer
Interdependence is when species in a community depend on each other for things such as food, shelter and pollination.
In a wood, a disease kills most of the rabbits. Suggest how this affects the foxes and the grass.
Mark scheme
- fewer foxes / foxes have less food (1)
- more grass / grass grows more because less is eaten (1)
Model answer
The foxes have less food, so their numbers fall. The grass is eaten less, so it grows more.
Nitrogen-fixing bacteria live in the roots of pea plants. Explain why this is an example of mutualism.
Mark scheme
- bacteria get sugars / food / shelter from the plant (1)
- plant gets nitrogen compounds / nitrates from the bacteria (1)
Model answer
Both species benefit: the bacteria get sugars from the plant, and the plant gets nitrogen compounds from the bacteria.
Which is an example of parasitism?
Choose one answer.
Correct Not quite: the answer is A tapeworm in a human gut
Mark scheme
C: a tapeworm in a human gut
Model answer
C: a tapeworm takes food from its host and harms it.
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