Topic 3.2: Natural Selection, Variation and Speciation Questions

Many fish stocks around the world have been fished beyond their limits. With reference to a named example, describe one impact of overexploitation on biodiversity.

A motorway is built through a large woodland. Define the term habitat fragmentation.

Mangrove forests along the coast of Myanmar have been cleared for rice fields and shrimp ponds. Explain how habitat destruction can disrupt food webs.

Figure 1 is a fact file on the biodiversity of Brava, a made-up island. Figure 2 gives the numbers of native, endemic and extinct species in Brava, and Figure 3 shows its human population and native forest cover between 1700 and 2000.

Figure 1 is a fact file on the biodiversity of Koru, a made-up island. Figure 2 gives the numbers of native, endemic and extinct species in Koru, and Figure 3 shows its human population and native forest cover between 1500 and 2000.

In a savanna, illegal collectors capture wild parrots to sell as pets. Explain why the illegal pet trade can reduce biodiversity beyond the targeted species.

A coastal town has increasing plastic waste entering the sea. Explain how pollution can indirectly reduce biodiversity in a marine ecosystem.

A wetland is partly drained for a new road. Distinguish between habitat destruction and habitat fragmentation.

Kalahari scrubland in Botswana is being converted into irrigated cropland. The rufous-tailed shrike, a bird that nests on the ground and eats beetles, grasshoppers and small lizards, lives there. Explain the chain of processes by which this conversion could cause the local extinction of the shrike.

A road and farms have split a forest in Borneo into six small patches. Suggest two reasons why fragmented habitats can have a higher extinction risk than continuous habitats.

A dual carriageway now divides a population of badgers. Outline how habitat fragmentation can reduce gene flow in a population.

Which pair of criteria is used to identify a biodiversity hotspot?

Figure 1 is a fact file on the biodiversity of Tamara, a made-up island. Figure 2 gives the numbers of native, endemic and extinct species in Tamara, and Figure 3 shows its human population and native forest cover between 1640 and 2000.

The last two wild ʻalalā (Hawaiian crows) disappeared in 2002. About 100 now live in two breeding centres in Hawaii, and attempts to return them to the forest have so far failed. Identify the IUCN Red List category of the ʻalalā.

Rangers discover traps set in a protected forest to catch wildlife for meat and trade. Identify one direct threat to biodiversity shown in this situation.

A national park in Kenya faces elephant poaching and the spread of farmland along its borders. Distinguish between direct and indirect threats to biodiversity, using one example of each.

By 1995 only about 25 Florida panthers were left, cut off from other big cats by highways and towns. Explain how inbreeding can increase in small, fragmented populations.

Hunters in a savanna have removed most of the antelope. Explain how overexploitation of a herbivore could indirectly affect plant biomass in an ecosystem.

Figure 1 shows the catch and the estimated stock of hake in a fishery between 2017 and 2020.

The Amur leopard cat is a small predator that lives at low density and has a large home range. It is often caught by accident in snares set for wolves and foxes. The Amur leopard, which shares its forest, has a large conservation programme, anti-poaching patrols and populations kept in zoos. Suggest two reasons why the Amur leopard cat may be at greater risk of extinction than the Amur leopard.