The engineers are back
386 words over 35 numbered lines, then 8 parts worth 16 marks (Linear Paper 2 (4BI1/2B) style, 14–18 marks). Read the article, answer each part, then open its mark scheme and set your mark.
Illustrative article written for Scholar Lab, not a Pearson text. The biology is real; the surveys, people and figures are invented or rounded for practice.
The engineers are back
Four hundred years ago, beavers were hunted to extinction in Britain
for their fur and meat. Now they are back. Small numbers have been
released in several river valleys, and a few have escaped from private
collections. Wherever they settle, they change the landscape.
Beavers cut down young trees with their teeth and use the branches,
mud and stones to build dams across streams. Behind each dam a pond
forms. The water flows more slowly, it becomes deeper, and more light
reaches the bottom of the shallow edges. Mud and silt settle out of
the slow water, and the ground around the pond stays wet all year.
Ecologists have found that these ponds increase biodiversity. Frogs,
newts, dragonflies and water birds move in, and new plants grow along
the muddy edges. In an illustrative survey, a student placed 20
quadrats, each 1 m², at random in the marshy ground beside a beaver
pond. She counted 140 marsh marigold plants in total. The marshy
ground covered an area of 1 200 m².
The dams also help people downstream. After heavy rain, each pond
fills and then releases water slowly, so flooding in towns is reduced.
Water leaving a series of beaver ponds can also contain much less
nitrate and phosphate than water entering them, because plants in the
ponds take up the ions and the silt traps them. This could reduce
eutrophication in rivers that flow through farmland, where fertiliser
washes off the fields after rain.
Not everyone is pleased. Some farmers complain that beavers flood
fields and block drainage ditches, and that they fell valuable trees.
In some areas, dams are now removed or lowered when they cause
problems, and a few beavers have been moved to new sites. Wildlife
groups argue that the benefits of beavers are greater than the costs,
and that farmers should be paid to leave a strip of wet land beside
each stream. A wide strip of wet woodland also gives shade that keeps
the water cool in summer.
Conservationists are also careful about where new beavers come from.
Many of the beavers released in Britain came from several different
countries in Europe, rather than from a single small population.
Before release, each animal is checked by a vet for parasites and for
diseases that could spread to other wild animals.
Read the article. Use the information in the article and your own knowledge to answer the questions. The lines in brackets show where to look; select them to highlight the text.
Use the information in the article and your own knowledge to answer the questions. The lines in brackets show you where to look; select them to highlight the text.
State what is meant by the term biodiversity.
(1)Give two abiotic factors that change when a beaver dam is built.
(2)Calculate an estimate of the number of marsh marigold plants in the marshy ground.
(2)Describe how the student could place the quadrats at random.
(2)Explain how beaver ponds could reduce the death of fish in rivers that flow through farmland.
(3)Explain why cutting down young trees can increase the number of plant species growing near the pond.
(2)Suggest two reasons why some people living near the river might support the return of beavers, other than the effects on wildlife.
(2)Explain why it is better to release beavers from several different populations than from one small population.
(2)Total for this question: 16 marks
0 / 16 marks · 0 of 8 parts rated
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