Nutrient cycle

Question 1

What happens when fossil fuels are burnt

Answer 1

The carbon in the fossil fuels is changed to carbon dioxide and goes into the air

This increases the amount of CO₂ in the air

Question 2

In photosythesis trees put…

Answer 2

More oxygen back into the air than they put back through respration

Question 3

If trees are cut down…

Answer 3

Less photosynthesis occurs

So less CO₂ is removed from the air

Question 4

If we burn trees

Answer 4

The carbon in their bodies is returned to the air

Question 5

In the nitrogen cycle, why must N₂ (g) be changed into nitrogen compounds like NO^3- and NH₄⁺?

Question 6

Nitrogen fixation

Answer 6

Changing N₂ into a more reactive form that plants can use

Question 7

How does nitrogen fixation happen

Answer 7

1. ) Lightning causes nitrogen and water in the air to form NO^3- ions (nitrates)
2. ) Nitrogen fixing bacteria changes nitrogen gas to ammonium ions (NH_4⁺)

Question 8

In soil, what does nitrifying bacteria do?

Answer 8

It changes ammonium ions to nitrate ions

Question 9

Nitrification

Answer 9

In soil when nitrifying bacteria change nitrate ions and ammnium ions

Question 10

What are nitrate ions used for?

Answer 10

To make amino acids

Amino acids are used to build up different proteins

Question 11

Denitrification

Answer 11

When a group of bacteria in the soil break down nitrate ions to form N₂ gas

Question 12

deamination

Answer 12

When when dead animal and plant’s proteins and amino acids are broken down by decomposers to produce ammonium ions