The Nitrogen Cycle

Question 1

What are the four reservoirs of nitrogen

Answer 1

• Atmosphere
• Biosphere
• Lithosphere
• Hydrosphere

Question 2

What form of nitrogen is in the atmosphere

Answer 2

In the form of N2 and some NOXs

Question 3

What form of nitrogen is in the biosphere

Answer 3

In the form of amino acids, proteins and DNA

Question 4

What form of nitrogen is in the lithosphere

Answer 4

Soil - ammonia, nitrates & nitrites
Some rocks contain nitrogen

Question 5

What form of nitrogen is in the hydrosphere

Answer 5

Some nitrites, nitrates and ammonia ions dissolved

Question 6

What is the process of ionisation

Answer 6

Processes such as lightning provide the energy for atmospheric nitrogen and oxygen to react and produce oxides of nitrogen

Question 7

What is the process of nitrogen fixation

Answer 7

Nitrogen fixation bacteria chemically reduce nitrogen to ammonia

Question 8

What is a characteristic of nitrogen fixating bacteria

Answer 8

They live in the soil or live symbiotically on the roots of legumes
E.g - peas, beans

Question 9

What is the process of nitrification

Answer 9

Involves the oxidation of ammonium ions to nitrites then to nitrites by nitrifying bacteria

Question 10

What is the process of food chain transfer

Answer 10

• Plants absorb nitrogen in the form of nitrates and nitrites
• Passed between organisms as animals eat the plants

Question 11

What is the process of denitrification

Answer 11

Chemical reduction of nitrates and nitrites in soil to nitrogen oxide gases by denitrifying bacteria in the soil

Question 12

What is the process of leaching

Answer 12

High solubility of nitrates means they are easily leached out of soils into water bodies where they act as nutrients for aquatic plants

Question 13

What is the process of absorption by roots

Answer 13

Plants absorb ammonia, nitrates and nitrites

Question 14

What is the process of ammonification

Answer 14

Micro-organisms such as bacteria & other types of decomposing micro-organisms break down nitrogen-containing chemicals from DOM into ammonia

Question 15

What does DOM stand for

Answer 15

Dead organic matter

Question 16

What condition does nitrification take place in

Answer 16

Aerobic

Question 17

What condition does nitrogen fixation take place in

Answer 17

Aerobic

Question 18

What condition does denitrification take place in

Answer 18

Anaerobic

Question 19

What are the three human activities that have an impact on the nitrogen cycle

Answer 19

• Haber process
• Agricultural processes
• Pollution

Question 20

What are the three types of agricultural processes that impact the nitrogen cycle

Answer 20

• Use of fertilisers
• Drainage systems
• Soil disturbance

Question 21

How does the Haber process impact the nitrogen cycle

Answer 21

The process in which a water body becomes overly enriched with nutrients, leading to the plentiful growth of algae

Question 22

How does the use of fertilisers impact the nitrogen cycle

Answer 22

Nitrate fertilisers increase problems caused by leaching including eutrophication if applied followed after rain or if applied nearby to a river

Question 23

How does the use of drainage systems impact the nitrogen cycle

Answer 23

Drained waterlogged fields make soil more aerobic encouraging more nitrogen fixation & nitrification.
Waterlogged/ flooded fields make soil more anaerobic encouraging nitrification.

Question 24

How does soil disturbance impact the nitrogen cycle

Answer 24

Increases rate of decomposition which increases ammonification

Question 25

How does pollution impact the nitrogen cycle

Answer 25

NOXs are released into the atmosphere by combustion processes Could increase the quantity of nitrates washed into the soil by precipitation

Question 26

What is eutrophication

Answer 26

the process by which a body of water becomes enriched with nutrients, leading to excessive growth of algae and other aquatic plants

Question 27

What is the process of eutrophication

Answer 27

- Agricultural runoff of fertilisers containing nitrogen cause excess nutrients to enter a body of water - Nutrients in water promote growth of algae - Algae bloom occurs preventing photosynthesis - Plants underneath die and decompose - Becomes a dead zone - Decomposition of aquatic species produces more nutrients increasing algae bloom

Question 28

What are 5 examples of how the nitrogen cycle can be sustainably managed.

Answer 28

- Crop rotation, increase planting of lagoons - Educate on application of fertilisers and weather conditions - Use more natural fertilisers - Intercept flow of water, collect & treat the water & reuse it - Reduce use of combustion engines, use catalytic converters or increase use of electric cars