Humans rely on plants for food because they are at the beginning of the food chain. We grow plants for direct consumption and to feed animals, which we then eat. Modern farming methods aim to increase plant and animal growth.

Fertilisers are chemicals that increase crop yields by providing minerals that plants need to grow (e.g. nitrates, phosphates and potassium) Minerals used up in crop growth are replaced by fertilisers so a lack of minerals doesn't limit growth of the next crop.

Antibiotics can be given to animals to increase food production as they kill or inhibit the growth of bacteria. Giving animals antibiotics mean they can use the energy on growing. It also allows them to digest more efficiently.

Selective breeding involves selecting plants with good characteristics to reproduce together in order to increase productivity.

Selective breeding can be used to increase the productivity of animals. Useful characteristics such as high meat, milk or egg yields can be developed.