3.5.4 Nitrogen cycle

Question 1

Molecules nitrogen are needed for

Answer 1

-DNA
-Amino acids
-ATP

Question 2

Nitrogen fixation

Answer 2

-Nitrogen-fixing bacteria in the soil or root nodules of plants converts nitrogen from the atmosphere into ammonia
-Ammonium makes amino acids which the plant can use to make proteins (mutualistic relationship with plant)

Question 3

Decomposition

Answer 3

-Nitrogen compounds in waste products (e.g. urine and faeces) and dead organisms are converted into ammonia by saprobionts
-This ammonia forms ammonium ions in the soil

Question 4

Nitrification

Answer 4

-The ammonium ions in the soil are converted by nitrifying bacteria into nitrites and then into nitrates

Question 5

Denitrification

Answer 5

-Dentiritifying bacteria convert nitrates into nitrogen gas
-Replenishing atmosphere