Teacher's notes and answers to questions in the book - Hodder Plus ...

WJEC GCSE Additional Science Teacher’s Notes
7
Biodiversity and the
environment
_How can biodiversity be maintained (pages 65–66)__
Questions
1. Suggest a possible reason for the decline in woodland birds since 1970.
Loss of habitat (tree felling)
Decrease in prey populations
Increase in predator populations
Disease
Loss of habitat is a more likely explanation than the others.
2. Suggest a possible reason for the decline in farmland birds since 1970.
As for Question 1. However, habitat loss is a less likely cause (though there has been some loss
on farmland), and decline in prey populations is a more likely cause, as much of their prey
would be insect pests which have been reduced by farmland management.
3. The graphs go up to 2008. What do you think would happen to the populations of the different types of
bird if further data had been published for 2010 Explain your answer.
Seabirds and water and wetland bird populations look roughly stable. Woodland birds have an
upturn in 2008 which might continue. Farmland birds seem to be in slow decline but the 2008
figure suggests this may be levelling off.
Note that for all three questions, definite answers cannot be given. Teachers should assess on the
basis of communication skills and the thought given to the answers. Answers should be reasonable,
and would be better if justified (Question 3 requires justification).
Discussion point
Suggest how the data in the graph might help to find reasons for the decline in woodland and farmland
birds.
There is no direct evidence in the graph for reasons for the decline. However, the graph does
provide some useful clues:
Significant decline in farmland birds started around 1980 and woodland birds around 1990. It
would be useful to look for any changes that took place in those habitats at those times.
The clear divergence in the different populations indicates that the cause is linked to the
habitat, it is not just something happening to birds in general.
_How can we get data about biodiversity in an_______
environment (pages 67–68)
Questions
4. Scientists sampled an area of 1000 m 2 on a beach that had an area of 1 km 2 (1 000 000 m 2 ). They
found 293 cockles. Estimate how many cockles there were on the whole beach.
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