Use Of Biological Resources. Food Production

Question 1

How glasshouses and polythene tunnels can be used to increase the yield of certain crops

Answer 1

1. Keeping plants enclosed in a glasshouse makes it easier to keep them free from pests and diseases
2. Commercial farms often supply artificial light after the sun goes down to give their plants more time to photosynthesise
3. Glasshouses trap the sun’s heat to keep the plants warm. In winter, a farmer might also use a heater to keep the temperature at the ideal lever
4. Farmers can also increase the level of CO2 in the glasshouse, for example by using a paraffin heater. As the paraffin burns, it makes CO2 as a by-product
5. By increasing the temperature and CO2 concentration, as well as the amount of light available, a farmer can increase the rate of photosynthesis for his or her plants. This means the plants will grow faster and bigger and crop yields will be higher

Question 2

Use of fertilizer to increase crop yield

Answer 2

1. Plants need certain elements e.g nitrogen so they can make important compounds like proteins.
2. If plants do not get enough of these elements, their growth and life processes are affected.
3. Sometimes these elements are missing from the soil because they have been used up by a previous crop
4. Farmers use fertilizers to replace these missing elements or provide more of them-this helps to increase the crop yield

Question 3

Reasons for pest control and the advantages and disadvantages of using pesticides and biological control with crop plants

Answer 3

1. Pests include microorganisms, insects and mammals. Pests that feed on crops are killed using various methods of pest control. This means fewer plants will be damaged or destroyed, increasing the crop yield.
2. Pesticides are a form of chemical pest control. They are often poisonous to humans, so they must be used carefully to keep the amount of pesticide in food bellow the safe level. Some pesticides also harm other wildlife
3. Biological control is an alternative to using pesticides. It means using other organisms to reduce the numbers of pests, either by encouraging will organisms or adding new ones
4. The helpful organism could be predators, parasites or disease causing
5. Biological controls can have a longer-lasting effect than spraying pesticides and be less harmful to wildlife. But introducing new organisms can cause problems-e.g cane toads were introduced to Australia to eat beetles, but they are now a major pest themselves because they poison the native species that eat them