Energy Transfers- Nutrient Cycles

Question 1

Name the four stages of the nitrogen cycle.

Answer 1

Ammonification, nitrification, dentrification and nitrogen fixation.

Question 2

What is the process of ammonification?

Answer 2

Saprobionts break down organic matter to ammonia in two stages- proteins are broken down into amino acids using protease, and deaminase enzymes remove amino groups.

Question 3

What is the process of nitrification?

Answer 3

Nitrifying bacteria convert ammonia to nitrate ions, NO3-, in an oxidation reaction, with an NO2- intermediate. Plants can take in nitrate ions through their roots.

Question 4

What is the process of denitrification?

Answer 4

Nitrate ions are converted into nitrogen gas by denitryfing bacteria. This process is wasteful and can be prevented from occuring by araeted and well-drained soil.

Question 5

What is the process of nitrogen fixation?

Answer 5

Nitrogen gas is fixed into other compounds by bacteria with nitrogen fixing ability. They do so by reducing nitrogen gas to ammonia which subsequently dissolves to form ammonium ions.

Question 6

Describe the phosphorus cycle.

Answer 6

1. Phosphate ions are released through the weathering of rocks, the decay of bones and shells and the excreta of some birds.
2. Plants absorb the phosphate ions through their roots assisted by the mycorrhizae, which increased the rate of absorption.
3. Consumers eat plants to obtain the phosphate.
4. Organic matter is broken down by saprobionic bacteria

Question 7

What is leaching?

Answer 7

The process by which mineral ions dissolve in rainwater and are carried from the soil to lakes and rivers.

Question 8

What is eutrophication?

Answer 8

Occurs as a result of leaching. Algea grows more rapidly due to additional nitrogen. This blocks out light from other plants, causing decay and the use of oxygen in the waterway. This leads to the death of the ecosystem.