Recycling within Ecosystems-The Nitrogen Cycle

Question 1

What do plants and animals need nitrogen for?

Answer 1

To make proteins and nucleic acids

Question 2

What percentage of the atmosphere is nitrogen?

Answer 2

78%

Question 3

What is the problem with the nitrogen stored in the atmosphere?

Answer 3

Plants and animals cannot use it in this form

Question 4

What do plants and animals need to use the nitrogen from the atmosphere?

Answer 4

Bacteria to convert atmospheric nitrogen into nitrogen containing compounds

Question 5

What are the 4 stages in converting atmospheric nitrogen to nitrogen containing compounds?

Answer 5

1)Nitrogen Fixation
2)Ammonification
3)Nitrification
4)Dentrification

Question 6

What happens in the first stage of the Nitrogen Cycle, Nitrogen Fixation?

Answer 6

Nitrogen gas is converted into ammonia by bacteria meaning it can then be used by plants

Question 7

In nitrogen fixation, where is Rhizobium and Azobacter found?

Answer 7

R-inside root nodules of leguminous e.g. peas
A-live inside soil and don’t have a mutalistic relationship

Question 8

What type of relationship does Rizobium form with the plants? and how?

Answer 8

A mutualistic relationship as they provide the plants with nitrogen compounds and the plant provides them with carbohydrates

Question 9

What happens in the second stage of the Nitrogen Cycle, Ammonification?

Answer 9

Nitrogen compounds from dead organisms are converted into ammonia by decomposers which turns into ammonium ions

Question 10

What substance also has the ability to form ammonium ions?

Answer 10

Animal waste as they contain nitrogen compounds

Question 11

What happens in the third stage of the Nitrogen Cycle, Nitrification?

Answer 11

Ammonium ions in the soil are changed into nitrogen compounds that can then be used by plants (nitrates)

Question 12

What are the two types of bacteria that are involved in nitrification?

Answer 12

-Nitrosomonas-convert ammonium ions into nitrites
-Nitrobacter-convert nitrites into nitrates which can then be used by plans

Question 13

What happens in the fourth stage of the Nitrogen Cycle, Denftrification?

Answer 13

Nitrates in soil converted back into nitrogen gas by dentrifying bacteria through respiration
-Happens under anaerobic conditions e.g. waterlogged soil

Question 14

How can nitrogen also be added to an ecosystem?

Answer 14

By Lightning (nitrogen fixation) or by artificial fertilisers