B3 Decompositions

Question 1

Why is decomposition importantly?

Answer 1

Without it dead organisms and waste would build up.

Question 2

Name the two main decomposers

Answer 2

Microorganisms such as fungi and bacteria.

Question 3

What factors affect the rate of decomposition?

Answer 3

Oxygen availability
Temperature
Water content

Question 4

How does oxygen availability affect decomposition?

Answer 4

At low oxygen levels the rate of decomposition is slower, because most decomposers need oxygen for aerobic respiration.

At high oxygen levels the rate of decomposers increase.

Some decomposers work anaerobically, but this transfers less energy, so these decomposers work more slowly.

Question 5

How does temperature affect the rate of decomposition?

Answer 5

Decomposers contain enzymes which digest the dead/waste material.

Decomposers usually work best in warm conditions, because the rate of enzyme controlled reactions varies with the temperature.

Question 6

At what temperature is the highest rate of decomposition?

Answer 6

50degrees c

Question 7

What role do enzymes play in decomposition?

Answer 7

The enzymes digest the dea/waste material.

Question 8

Why is decomposition slower at lower temperatures?

Answer 8

The rate of reaction is slower, because it doesn’t have enough energy.

Question 9

What happens to the enzymes when the temperature goes too high?

Answer 9

They are denatured and reactions stop.

Question 10

How does water content affect the rate of decomposition?

Answer 10

Waterlogged soils don’t contain much oxygen so the rate of reactions decrease.

The rate of reaction increase in moist conditions because decomposers need water to survive.

Question 11

What is global warming?

Answer 11

Increased levels of greenhouse gases causing the global temperature to rise.

Question 12

How do decomposers in landfill sites contribute to global warming?

Answer 12

Landfill sites tend to be low in oxygen, so there are lots of decomposers that respire anaerobically. Anaerobic respiration by decomposers produces methane which has a greater greenhouse effect than CO2, therefore landfill sites contribute more to global warming than natural decomposers in ecosystems.

Question 13

How to calculate the rate of decomposition

Answer 13

See p55

Question 14

Compost is decayed remains of animal and plant matter that can be used as fertilisers. Give two things you could do to make sure the compost decomposes quicker. (2 marks)

Answer 14

Make sure that plenty of oxygen can get in to the waste .

Keep the waste in a warm place

Make sure the waste is moist but not too wet