Nitrogen in Ecosystems

Question 1

Nitrogen cycle

This set of cards needs to be worked through in order.

Answer 1

They will help you to revise the nitrogen cycle by building up a diagram of it.

Question 2

Which chemicals are made, by all living things, using Nitrogen?

Answer 2

Amino acids, which are built into proteins.

Question 3

Lets think about why proteins are important to cells.

What are they used for?

Answer 3

To make:

1. Structures in the cell, including the cell membrane.
2. Enzymes.

Question 4

Lets start building up the Nitrogen cycle starting with Plant protein.

What happens to the protein present in plants?

Answer 4

1. Eaten by animals
2. Broken down when the plant dies.

Question 5

What happens to the animal protein?

Answer 5

1. Passes out in urine (and faeces)
2. Will be broken down when the animal dies

Question 6

What are the plant and animal proteins converted into, in the soil?

Answer 6

Ammonium

Question 7

Ammonium is converted into ……. and then ……..

Answer 7

Nitrite and then Nitrate

Question 8

The nitrate is then absorbed by the plant.

Which part of the plant absorbs the nitrate?

Answer 8

Root hairs

Question 9

Once inside the plant the Nitrate is used to produce ….

Answer 9

Amino acids, which are built up into Plant Protein.

This completes the basic Nitrogen Cycle!!

Question 10

Using the information on the last 8 cards, draw out the basic Nitrogen cycle.

Answer 10

It should look something like this:

Question 11

What name is given to the set of reactions from Ammonium to Nitrate?

Answer 11

Nitrification

Add this label to your diagram.

Question 12

There is a lot of Nitrogen gas in the air but plants can’t use it directly.

What is the name of the process that puts N₂ gas, from the air, into the Nitrogen cycle?

Answer 12

Nitrogen fixation

Question 13

Name the two places where nitrogen fixing bacteria are found.

Answer 13

1. Free-fixing bacteria in the soil (producing ammonium)
2. Inside root nodules of some plants (making nitrates for the plant to use).

Question 14

Name the chemical, containing nitrate, which farmers and gardeners add to the soil to impove plant growth.

Answer 14

Fertiliser

Question 15

Name the bacteria that convert Nitrates back into N₂ gas in the air.

Answer 15

Denitrifying bacteria

Question 16

Add the information from the last five cards to your diagram.

Answer 16

Your cycle should now look something like this: