Key Area 5 - Food Production

Question 1

Why do food yields increase as human population increases?

Answer 1

As it has become increasingly important that enough food is produced for everyone

Question 2

Why are nitrates used in fertilisers?

Answer 2

As nitrogen is essential for the formation of amino acids in proteins. However, it is unreactive so cannot be directly used by plants so are dependent on other processes to covert nitrogen gas into nitrates in the soil. The nitrates dissolved in the soil water are absorbed into plants

Question 3

What are the Intensive Farming Techniques?

Answer 3

• The use of fertilisers ensure crops have sufficient nutrients (nitrates and phosphates) for rapid and healthy growth, therefore increasing crop yield
• The use of pesticides ensure pests don’t reduce crop yields by feeding on and damaging crops

Question 4

How do animals obtain amino acids?

Answer 4

By consuming plant and/or animal proteins.

Plants absorb nitrates dissolved in soil water and use them to make amino acids and other molecules

Question 5

Why are fertilisers added to land?

Answer 5

To increase the levels of nitrates and other nutrients as they are being used up by the plants/crops being grown

Question 6

What is leaching?

Answer 6

When fertilisers dissolve in soil water and run off into nearby bodies of water (rivers or lochs). This increases the nitrate levels and the algae present in the water can multiply rapidly increasing their population size

Question 7

What is an algal bloom (also known as eutrophication)?

Answer 7

The increase of algae present in a body of water

Question 8

Give the effects of an algal bloom

Answer 8

1. Thick layer of algae forms on surface, reducing light levels in water below
2. Aquatic plants living below water no longer able to photosynthesise and eventually die
3. Dissolved oxygen levels in the water decrease die to lack of photosynthesis
4. Water can’t sustain large population of algae, the algae dies
5. Dead algae and aquatic plants provide large food source for bacteria in the water which multiply rapidly
6. Increased population of bacteria does lots of aerobic respiration, further using up dissolved oxygen in water
7. Oxygen levels too low for most marine mammals and remaining plants to survive, leading to a loss of biodiversity in the ecosystem

Question 9

Animals obtain the nitrogen required to produce protein by consuming plants

Answer 9

.

Question 10

What is bioaccumulation?

Answer 10

The increase in concentration of toxic substances inside living organisms, as some pesticides are not biodegradable

Question 11

Bioaccumulation can result in biomagnification, what is this?

Answer 11

The concentration of a pesticide in the body tissues of organisms becomes higher at higher levels of a food chain, due to the biomass the organisms are consuming. The higher pesticide concentration can cause its toxicity to reach lethal levels in organisms at the top of food chains

Question 12

Give two alternatives to using pesticides

Answer 12

GM crops and biological control
GM Crops can be resistant to disease and pests
Biological control involves introducing a predator to prey on a pest species. The organism used to reduce the lest population is called a biological control agent

Question 13

What is biological control?

Answer 13

The introduction of a predator to prey on a pest species. The organism used to reduce the pest population is called a biological control agent.

(e.g using ladybirds to control greenfly populations)