Ecology and the Environment - Cycles Within Ecosystems (Paper 2)

Question 1

what are the stages in the nitrogen cycle?

Answer 1

nitrogen fixation, absorption, movement along food chain, death and denitrification

Question 2

how does nitrogen fixation contribute to the nitrogen cycle?

Answer 2

nitrogen gas in the atmosphere is too unreactive to be used directly
nitrogen-fixing bacteria converts nitrogen gas into nitrates for use by plants
lightning converts nitrogen into nitrates
Haber process in soil converts nitrogen into ammonia, which nitrifying bacteria converts into nitrates

Question 3

how does absorption by plants contribute to the nitrogen cycle?

Answer 3

plants will absorb nitrates through their roots, producing amino acids that form proteins

Question 4

how does movement along the food chain contribute to the nitrogen cycle?

Answer 4

animals in the food chain consume plants to absorb nitrogen found in plant protein, so nitrogen is passed along the food chain

Question 5

how does the death of organisms contribute to the nitrogen cycle?

Answer 5

decomposers break down dead organisms and waste products to return nitrogen compounds to the soil

Question 6

how does denitrification contribute to the nitrogen cycle?

Answer 6

denitrifying bacteria in soil will break down nitrates to return nitrogen gas into the air