May/June 2026 Paper 42

Describe what is meant by a sustainable resource.

Tilapia is a type of fish that is eaten by many people around the world. In the wild, tilapia feed on producers. Fish farmers grow these fish in water in outdoor ponds. The ponds are positioned to maximise access to sunlight. Suggest how maximising sunlight leads to an increase in the growth of tilapia.

Tilapia are a good source of protein. Some farmers add waste organic material to the ponds as a source of mineral ions for the fish. State the name of the mineral ion that provides an element found in all proteins.

State one reason why proteins are important in the human diet.

State the name of a process that could occur if the farmer adds excessive waste organic material to the pond.

One way of conserving wild fish stocks is to regulate the size of the holes in the nets that are used to catch the fish. Explain how this helps to conserve fish stocks.

Some species are threatened with extinction. Explain the reasons why species become endangered.

Organisms can be conserved in captive breeding programmes by using the techniques of artificial insemination (AI) and in vitro fertilisation (IVF). Describe the processes of artificial insemination (AI) and in vitro fertilisation (IVF). artificial insemination (AI) in vitro fertilisation (IVF)