Conservation

Question 1

Function of chlorine in a water purification system

Answer 1

Chlorine helps kill bacteria, as some may be pathogenic

Question 2

Explain the roles of bacteria in a sewage works’ aerobic digestion tank:

Answer 2

• secretes enzymes
• breaks down insoluble substances to soluble substances
• breaks down proteins to amino acids using protease
• breaks down starch to sugar using amylase
• breaks down fat to fatty acids and glycerol using lipase

Question 3

How is nitrogen in dead leaves recycled to be reabsorbed?

Answer 3

1. Decomposers (bacteria, fungi) secrete protease to break down protein to amino acids
2. Amino acids are converted to ammonia
3. Deamination occurs
4. Ammonia are converted to nitrites
5. Nitrites are converted to nitrates
6. Nitrification occurs
7. Nitrates are then absorbed by plants

Question 4

Process of converting atmospheric nitrogen:

Answer 4

Nitrogen fixation

Question 5

How does nitrogen fixation occur?

Answer 5

• root nodules on legumes
• free living nitrogen-fixing bacteria
• nitrogen is converted to ammonia

Question 6

Sewage treatment processes:

Answer 6

1. Filtration/screening to remove large pieces of waste
2. Flocculation/coagulation to separate suspended particles from water
3. Digestion by decomposers
4. Sludge treated with anaerobic decomposers
5. Water is then treated with chlorine/UV light/ozone
6. Distillation/collection of water from evaporator

Question 7

Environmental damage caused by herbicides:

Answer 7

• kills other plants as well as weeds
• bioaccumulation
• destroys habitats
• harms insects/animals
• weeds may gradually build up a resistance to herbicides