Biology 9700 · AS & A Level · Natural and artificial selection
Natural and artificial selection — practice question
Sarawak is a region in south-east Asia and is mostly covered by tropical rainforest. Logging has been permitted in large areas of the forest. A study was carried out to estimate the population size of different species of mammals living in the rainforest:
• before any logging took place
• straight after logging
• two years after logging
• four years after logging.
Table 8.1 gives the results of the study for six mammal species. When the numbers were too small for population density to be measured, the species were recorded as "present".
(a)[2]
Calculate the percentage increase in the small squirrel population from before logging to two years after logging.
Show your working.
(b)[4]
Suggest why populations, such as that of the small squirrel, do not keep increasing without limit.
(c)[2]
Suggest why marbled cats and small-clawed otters became extinct in this area, whereas the other mammals did not.
Worked solution & mark scheme
This 8-mark question has a full step-by-step worked solution and mark scheme. One marking point: “$550\%$” …