Nitrogen cycle

Question 1

Nitrogen Cycle

Answer 1

The nitrogen cycle transforms and circulates nitrogen in various forms through Earth’s spheres.

Question 2

Atmospheric nitrogen fixation

Answer 2

Lighting strikes generate enough energy to separate nitrogen gas (N2) into nitric oxide (NO) and nitrogen dioxide (NO2)
These smaller molecules dissolve in water droplets in clouds – forming nitric acid.
Nitric acid is transported to the Earth’s surface through precipitation.

Question 3

Nitric acid

Answer 3

Nitric acid is the inorganic compound with the formula H N O 3. It is a highly corrosive mineral acid.

Question 4

Assimilation

Answer 4

Assimilation of nitrites, nitrates and ammonia by plants
Plants and some microorganisms take up ammonium (NH4+), and nitrate ions from the soil to use in cell processes.

Question 5

Consumption

Answer 5

Animals acquire organic nitrogen by consuming plants or other animals.

Question 6

Ammonification

Answer 6

Decomposers (bacteria and fungi) break down nitrogen compounds found in dead organisms and other organic matter.
Converts them to ammonia or ammonium ions.
These more simple forms of nitrogen are released back into the soil.

Question 7

Volcanic eruptions

Answer 7

Volcanic eruptions release nitrogen gas straight into the atmosphere.
Heat and pressure created by eruptions leads to transformation of atmospheric nitrogen into nitrogen oxides.
Reacts with water vapour to form precipitation.

Question 8

Denitrification

Answer 8

Denitrifying bacteria convert nitrate (NO3-) and nitrate (NO2-) ions into nitrogen gas.
Nitrogen gas is returned to the atmosphere, where it can be accessed again by nitrogen-fixing bacteria.

Question 9

Nitrogen fixation by bacteria

Answer 9

Atmospheric N2 is converted into ammonia or ammonium ions by nitrogen-fixing bacteria found in the soil.

Question 10

Nitrification

Answer 10

Ammonia (from nitrogen fixation) is converted to nitrite ions by nitrifying bacteria.
Nitrite ions are then oxidized into nitrate ions by other nitrifying bacteria. (Nitrobacter)

Question 11

Deforestation and fires

Answer 11

When trees and vegetation are cut down, burned or left to decay, the carbon stored in their tissues and cells is released into the atmosphere as CO2. Also results in the loss of carbon sinks.