Nitrogen cycle

Question 1

what are the 4 steps of the nitrogen cycle

Answer 1

nitrogen fixation
ammonification
nitrification
denitrification

Question 2

describe nitrogen fixation

Answer 2

N gas in air fixed by nitrogen fixing bacteria free living or mutualistic. converted to ammonia then ammonium ions

Question 3

describe nitrification

Answer 3

carried out by nitrifying bacteria convert ammonium ions to nitrite then nitrate in an oxidation reaction. nitrate then taken up by plants through roots used to make proteins DNA etc

Question 4

describe ammonification

Answer 4

saprobionts break down proteins in dead plants and animals into amino acids then ammonium. they release enzymes (extracellular digestion) to break down proteins and then absorb products by diffusion this is called saprobiotic nutrition

Question 5

describe denitrification

Answer 5

by anaerobic denitrifying bacteria convert nitrate back into

Question 6

why do farmers plough

Answer 6

increase oxygen in soil. nitrifying bacteria saprophytic bacteria + n fixing bacteria respire aerobically. more nitrates for plants. less nitrate conveted back to gas by denitrifying bacteria which respires anaerobically

Question 7

what does mycorrhizae do

Answer 7

help a plant take up water and inorganic ions through the root of the plant by increasing the length of time theyre held in the soil around the roots