5a

Question 1

How can greenhouses increase the yield of crops?

Answer 1

Can provide artificial lighting, warmth and CO2. They are limiting factors for photosynthesis. More photosynthesis —> More yield.

Question 2

Effects of increased carbon dioxide and increased temperature on crop yield

Answer 2

Crop yield is increased. They all limit the rate of photosynthesis and therefore growth.

Question 3

How can fertilizer increase crop yield

Answer 3

Fertilizers provide mineral ions to the soil. Plants (crops) need these mineral ions for growth. Fertilizers can therefore increase yield.

Question 4

Why are pesticides used

Answer 4

Pesticides eliminate pests that reduce the yield of a crop.

Question 5

Fertiliser Contents

Answer 5

NPK

Question 6

Types of pesticides

Answer 6

Herbicides
Insecticide
Fungicide
Moluscide

Question 7

Pesticide Problems

Answer 7

• Persistent
• Resistance develops
• Bioaccumulation
• Toxic (kills bees)

Question 8

Fish Farming

Answer 8

Fish are farmed because they are a source of high-quality protein. They are farmed in densely stocked enclosures in rivers, lakes, or the sea.

Advantages:
- Water quality can be monitored
- The diet of the fish can be carefully controlled
- Selective breeding programs can increase the quality of the fish
- Fish are protected from predators

Question 9

Role of lactobacilus

Answer 9

• Used in yogurt production
• Breaks down lactose into lactic acid

Question 10

Role of yeast

Answer 10

• Bread and beer production
• Respire anaerobically to release ethanol and carbon dioxide
• Carbon dioxide to make bread rise. Ethanol to give alcoholic content.

Question 11

Fermentor

Answer 11

• Used to give suitable conditions for the growth of microorganisms
• Control: temperature, nutrition, pH, sterelisation, oxygentaion…