topic 9 - ecosystems (nitrogen cycle)

Question 1

crop rotation

Answer 1

where a different crop is planted in the same field each year in a 3 or 4 year cycle, such as potatoes, oats beans and cabbages. This helps to control the build-up of soil pests for each crop

Question 2

manure

Answer 2

a mixture containing animal waste that is added to soil to improve its fertility

Question 3

nitrate

Answer 3

a compound that contains nitrogen in the form of a nitrate ion

Question 4

nitrogen cycle

Answer 4

a sequence of processes by which nitrogen moves from the atmosphere through living and dead organisms, into the soil and back to the atmosphere

Question 5

nitrogen-fixing bacteria

Answer 5

bacteria that can take nitrogen from the atmosphere and convert it to more complex nitrogen compounds such as ammonia

Question 6

nitrifying bacteria

Answer 6

turn ammonia in decaying matter into nitrites then into nitrates

Question 7

denitrifying bacteria

Answer 7

turn nitrates back into N2 gas. This is of no benefit to living organisms. Often found in waterlogged soils