SB9l The nitrogen cycle

Question 1

Why is Nitrogen important?

Answer 1

Nitrogen (N2) is essential for growth because it is used by plants and
animals to make proteins and DNA

Question 2

What do nitrogen fixing bacteria do?

Answer 2

Converted nitrogen into nitrates

Question 2

What do Nitrifying bacteria do?

Answer 2

convert ammonia (NH3) to nitrates (NO3).

Question 3

What do Denitrifying bacteria do?

Answer 3

convert nitrates(NO3) to nitrogen (N2)

Question 4

Explain the steps in the full cycle of nitrogen starting from the air.

Answer 4

1. Nitrogen (N2) goes from the air into the soil (by diffusion or lightning).
2. Converted to nitrates (NO3) by nitrogen fixing bacteria.
3. Plants absorb nitrates from their roots by active transport and use it to
   produce proteins (assimilation).
4. Animals eat the plants and grow .
5. Animals release faeces, urine or may die giving ammonia into the soil
6. Nitrifying bacteria convert ammonia (NH3) to nitrates (NO3).
7. Denitrifying bacteria convert it back to nitrogen (N2) and release it into
   the air