Nitrogen Cycle

Question 1

Nitrogen fixation

Answer 1

• nitrogen fixing bacteria can synthesis nitrogen compounds from nitrogen gas
• some live in the soil but others live in root nodules on leguminous plants
• the bacteria in root nodules of plants form a mutualistic relationship in which both organisms benefit from association
• the plants get nitrates from bacteria
• the bacteria gets sugar (glucose) from the plants

Question 2

Ammonification

Answer 2

• decomposes digest proteins from dead producers and consumers to form amino acids
• the amino acids are converted to ammonium ions in the soil

Question 3

Nitrification

Answer 3

• nitrification of is carried out in 2 stages by 2 different species of nitricying bacteria
• first product made is nitrites , and then nitrates
• energy released during these reactions is used by the bacteria

Question 4

Denitrification

Answer 4

• in soils where little or no oxygen is available e.g. Water logged soil and/or poor aerated soil
• denitrifying bacteria release nitrogen into the air and reduce nitrates in the soil
• this is not good for plant growth

Question 5

Summarised nitrogen cycle

Answer 5

• green plants absorb nitrogen as nitrates from the soil
• they use the nitrogen in the nitrates to make proteins and amino acid
• when the plants are eaten by animals, some of the nitrogen becomes part of the proteins in their body
• decomposes such as bacteria and fungi break down the dead animals and plants, producing ammonium compounds
• ammonium compounds are converted to nitrites, then nitrates be nitrifying bacteria
• nitrogen from the soil is released back into the atmosphere by denitrifying bacteria
• nitrogen gas in the air can be fixed by nitrogen fixing bacteria in root nodules of legumes