The Nitrogen Cycle

Question 1

function

Answer 1

to convert unreactive atmospheric nitrogen into useful compounds eg nitrates, which can be used by organisms

Question 2

why we need nitrogen

Answer 2

to form proteins
eg enzymes
and DNA structure

Question 3

other sources of fixed nitrogen/nitrates

Answer 3

fertilisers

Question 4

role of animals and plants in nitrogen cycle

Answer 4

plants absorb nitrates through their roots
nitrogen is taken in by animals when they eat plants
plants and animals die and decay and can be converted to ammonia by decomposers

Question 5

nitrogen fixing bacteria

Answer 5

convert atmospheric nitrogen to nitrates to plant roots
form a symbiotic relationship with legumes
-they provide nitrates to these plans while they obtain carbohydrates for themselves and live at the plants roots
-animals excrete urine which contains ammonia

Question 6

role of decomposers

Answer 6

break down dead and decaying animals and plants and release ammonia (NH2) into soil

Question 7

nitrifying bacteria

Answer 7

convert ammonia to nitrites to nitrates

they are chemosynthetic - make their own food from chemical reactions

Question 8

denitrifying bacteria

Answer 8

convert soil nitrates to atmospheric nitrogen

significant as they ensure that nitrogen levels in the atmosphere are always constant

Question 9

nitrogen cycle steps (learn diagram!!!!!)

Answer 9

1. nitrogen fixation
2. decomposition
3. nitrification
4. denitrification