Food Production: Answers

Describe the ways in which a farmer can increase crop yields.

Farmers can grow crops in greenhouses which enable conditions such as temperature, light intensity, carbon dioxide concentration and moisture to be carefully controlled. Polythene tunnels can also be used to protect crops from wind, rain and extreme temperature. Fertilisers can be added to make the soil more fertile and pesticides can be used to kill any organisms which may eat or compete with the crops. Biological control is also a method to kill any animals which may feed on the crops.

Why does temperature affect the growth of a plant?

Temperature affects growth rates of a plant because photosynthesis is a process which is controlled by enzymes. Enzymes work slowly at low temperatures because they have low kinetic energy and can become denatured at high temperatures.

Give three advantages to using biological control instead of using pesticide.

Biological control lasts longer than pesticides. Whenever it rains, the pesticide will be washed away and will need to be reapplied. Biological control is specific to a certain organism - for example cats can be brought into a farm to kill mice and we don’t need to worry about other organisms being affected. Pesticide is non-specific which means it will kill a range of organisms, not just the pests. Pests can develop resistance to pesticide which is not an issue when using biological control. Finally, pesticide can build up in the food chain (bioaccumulation) which may have health consequences for consumers. Again, this is not an issue for biological control.

What is the name of the bacteria used in the manufacture of yoghurt.

Lactobacillus bacteria are used in yoghurt production. They convert lactose into lactic acid.

Explain how temperature is controlled inside a fermenter.

Temperature is controlled by a thermometer which is connected to a sensor. Fluctuations in temperature can be adjusted by changing the temperature of the water inside the water jacket which surrounds the fermenter.

Explain the methods used to produce a large number of fish in a fish farm.

On a fish farm the water will be cleaned regularly to remove the build up of waste and to remove any pathogens to prevent disease. The farmers may give the fish antibiotics which will also prevent disease. The farmers are likely to separate fish of the same species to reduce intraspecific competition and separate fish of different species to reduce interspecific competition. Protective measures such as scarecrows and fencing can be used to prevent predation of the fish. The fish will be fed frequently and in small amounts, which prevents the accumulation of food in the pond and helps the fish to grow quickly. The farmers may choose to selectively breed fish or to grow fish which have been genetically modified to grow faster.