Nitrogen cycle

Question 1

describe nitrogen

Answer 1

unreactive so needs to be converted into nitrates to be directly used by plants and animals needed for making proteins for growth

Question 2

name the four types of bacteria

Answer 2

• decomposers
• nitrifying bacteria
• nitrogen fixing bacteria
• denitrifying

Question 3

describe decomposers

Answer 3

decomposes proteins into ammonia to form ammonium ions in soil

Question 4

describe nitrifying bacteria

Answer 4

turn ammonium into nitrites and nitrates

Question 5

describe nitrogen fixing bacteria

Answer 5

turn nitrogen into ammonia / ammonium ions

Question 6

denitrifying bacteria

Answer 6

turn nitrates back into nitrogen often found in waterlogged soils

Question 7

how can nitrogen fixing happen

Answer 7

• lighting energy can cause nitrogen in air to react with oxygen and produce nitrates
• lives in soils and roots / roots of beans and peas when decompose return to soil.

Question 8

what are the two ways farmers can increase amounts of nitrates in the soil

Answer 8

using crop rotation and fertillisers

Question 9

how does crop rotation increase nitrate in soil

Answer 9

• different crops grown in cycle including nitrogen fixing crop which puts nitrates back into soil for following year

Question 10

how do fertilisers increase nitrates in soil

Answer 10

spreading animal manure and compost recycles the nutrients as it is returned to the soil by decomposition
- using artificial fertiliser containing nitrates can be expensive though