Topic 9 - Increasing Crop Yield

Question 1

how does keeping plants in glasshouses help increase the rate of photosynthesis?

Answer 1

1. makes it easier to keep them from pests and diseases
2. helps farmers control water supply
3. artificial light can be supplied after the sun goes down
4. heat is trapped, and in winter a heater can be used
5. carbon dioxide levels can be increased

Question 2

why do farmers use fertilisers?

Answer 2

to ensure plants get enough of the minerals they need, especially if these minerals are missing from the soil as they’ve been used up by a previous crop

Question 3

why do farmers use pest control?

Answer 3

to reduce damage to plants, increasing yield

Question 4

what are pesticides?

Answer 4

a form of chemical pest control

Question 5

why does pesticide use need to be controlled?

Answer 5

they’re often poisonous to humans, so they must be used carefully.

Question 6

what is biological control?

Answer 6

an alternative to using pesticides. it means using other organisms to reduce the number of pests.

Question 7

what are examples of organisms that could be used for biological control?

Answer 7

1. predators - e.g. ladybirds eating aphids
2. parasites - e.g. flies that lay eggs on slugs, eventually killing them
3. disease-causing - e.g. bacteria that affect caterpillars

Question 8

what are the positives to biological control?

Answer 8

the effects are longer-lasting and less harmful to wildlife

Question 9

what are the negatives to biological control?

Answer 9

organisms introduced to kill pests might become pests themselves