Ecosytems

Question 1

What things act as decomposes (3)

Answer 1

• microorganisms
• bacteria
• fungi

Question 2

Do microorganisms contribute CO2 to the atmosphere

Answer 2

Yes as they respire

Question 3

What do microorganisms feed on

Answer 3

Plant and animal material

Question 4

Why do microorganisms feed on material

Answer 4

For growth and other life processes

Question 5

What happens when decay is prevented

Answer 5

Fossil fuels are formed.

Question 6

What do fossil fuels store

Answer 6

Energy in carbon compounds

Question 7

What nutrients are released in decay

Answer 7

Nitrates and phosphates

Question 8

What are nutrient cycles like in stable communities

Answer 8

The processes that remove materials are balanced by the processes that return materials.

Question 9

How is carbon released into the atmosphere

Answer 9

• combustion of fossil fuels
• respiration

Question 10

How is carbon absorbed from the atmosphere (biology) (2)

Answer 10

• photosynthesis
• passed to animals when they eat plant (forms their carbohydrates, fats and proteins)

Question 11

What enzyme converts urea to ammonia

Answer 11

Urease

Question 12

What things can be converted into ammonia

Answer 12

Protein and urea

Question 13

What can ammonia be converted to

Answer 13

Nitrates

Question 14

Nitrogen fixation

Answer 14

Nitrogen from the air is converted to nitrates.

Question 15

Where does nitrogen fixation occur

Answer 15

In free living bacteria in the soil and in bacteria in root nodules of legume plants. Or lightning

Question 16

Denitrification

Answer 16

Break down of nitrates into nitrogen gas

Question 17

Denitrifying bacteria

Answer 17

Some bacteria in the soil break down nitrates into nitrogen gas

Question 18

Where do denitrifying bacteria usually live

Answer 18

Waterlogged/unploughed soil

Question 19

What factors affect bacterial action and influence decomposition (4)

Answer 19

• temperature
• oxygen
• pH
• heavy metals

Question 20

What are the effects of rising human population (3)

Answer 20

More space is needed for
- housing
- agriculture
- industry

Question 21

Advantages of intensive farming

Answer 21

• increased crop yield and high levels of meat production

Question 22

Disadvantages of intensive farming (3)

Answer 22

• fertilisers and pesticides - chemicals being washed from soil to waterways
• disease control - excess use of antibiotics in animals causes increased bacterial resistance
• battery methods - negative effect on animal welfare