the nitrogen cycle (ppr 2)

Question 1

what is a saprobiont

Answer 1

bacteria/fungi that break down the remains or waste products of other organisms that contain organic nitrogen

Question 2

why is nitrogen needed

Answer 2

for making amino acids in proteins, nucleic acids, ATP (,makes up 78% of the atmosphere)

Question 3

what is symbiosis

Answer 3

evolved interactions or close living relationship between organisms from different species, usually with benefits to one or both individuals involved

Question 4

what are the 4 stages of the nitrogen cycle

Answer 4

nitrogen fixing, ammonification, nitrification, denitrification

Question 5

what is nitrogen fixing

Answer 5

atmospheric nitrogen is reduced to ammonia by rhizobium. occurs in 2 ways:
- free living soil bacteria
- symbiotic relationship between leguminous plants containing rhizobium in root nodules

Question 6

what is ammonification

Answer 6

decomposers convert organic nitrogen compounds into ammonia or ammonium ions
- nitrogen compounds in plants can be passed to animals by feeding

Question 7

what is nitrification

Answer 7

-aerobic nitrifying bacteria in soil (well aerated)absorb and oxidise ammonium ions to nitrites or oxidise nitrites into nitrates
-oxidation reactions release energy used by chemotrophic bacteria to carry out chemosynthesis

Question 8

what is denitrification

Answer 8

nitrates in the soil are converted into nitrogen gas by denitrifying bacteria
- anaerobic denitrifying bacteria use nitrates as an alternative to oxygen for the final electron acceptor in respiration to produce N2