nutrient Cycles

Question 1

Describe the phosphate cycle

Answer 1

Rocks contain phosphate.

Harsh weather conditions break down rocks, releasing phosphate into the soil.

Some of this phosphate is absorbed by plants to make phosphate-containing compounds like ATP.

Plants are eaten by animals, which can then make their own phosphate-containing compounds. Plants and animals die, and animals also excrete. The waste of animals and plants is broken down by saprobionts, releasing phosphate back into the soil.

Some phosphate moves throughout the soil to bodies of water, like the sea.

Over thousands of years phosphate is used to form new rocks - after which the phosphorus cycle repeats.

Question 2

Nitrogen fixation

Answer 2

Nitrogen enters soil in air pockets. Nitrogen-fixing bacteria convert it into ammonia. If ammonia comes into contact with water in the soil, it becomes ammonium ions.

Question 3

Nitrification

Answer 3

Plants absorb nitrogen through nitrates in the soil.

First, ammonium ions are converted to nitrite, which is then converted to nitrate.

The process of converting ammonium ions to nitrate is known as nitrification.

The bacteria that carry out nitrification are called nitrifying bacteria.

In order to carry out nitrification, nitrifying bacteria need oxygen.

Question 4

Denitrification

Answer 4

The process of converting nitrate to nitrogen gas is known as denitrification. This is carried out by denitrifying bacteria which undergo Anaerobic respiration.

Question 5

Extra knowledge: bacteria names

Answer 5

Nitrogen fixing:
Mutualistic nitrogen-fixing bacteria: Rhizobium.

Mutualistic fungi are called mycorrhizae

Nitrifying:
Converts nitrite to nitrate: Nitrobacter.

Question 6

Ammonification

Answer 6

Nitrogen-containing compounds (amino acids, DNA etc) in waste are broken down by saprobionts, forming ammonia.

This ammonia is released into the soil forming ammonium ions.

Question 7

Plants absorb nitrogen in the form of…

Answer 7

Ammonia and nitrate

Question 8

Benefits of mycchorizae

Answer 8

1. It increases the root’s surface area for water and mineral uptake, increasing the plant’s chances of survival.
2. The fungi act as a sponge and hold onto water, which is especially helpful if there’s a drought.