6.3.1 (c) Nitrogen Cycle

Question 1

organic compunds in living organisms which contain nitrogen?

Answer 1

• amino acids
• nucleic acids

Question 2

what is nitrification?

Answer 2

conversion of ammonia into nitrites and then nitrates

Question 3

bacteria needed for ammonia to nitrite?

Answer 3

nitrosomonas

Question 4

bacteria needed for nitrite to nitrate?

Answer 4

nitrobacter

Question 5

how is nitrogen taken up in a plant?

Answer 5

nitrate ions are very soluble so can be easily taken up by plants

Question 6

what is ammonification?

Answer 6

decomposers convert nitrogen containing molecules into ammonium in the soil

Question 7

ammonification equation?

Answer 7

NO3- to Ammonia

Question 8

difference between decomposers and detritivores?

Answer 8

detritivores break down decaying material into smaller pieces to give a larger surface area

decomposers feed on decaying material (therefore saprophytes)

Question 9

what is denitrification?

Answer 9

conversion of nitrates to nitrogen gas

Question 10

bacteria needed for denitrification?

Answer 10

pseudonomas

bacteria uses nitrates for respiration and produce nitrogen gas

Question 11

conditions needed for denitrification?

Answer 11

anaerobic conditions (waterlogged soil)

Question 12

conditions of soil in nitrogen cycle?

Answer 12

needs space for oxygen to allow for aerobic respiration in bacteria which power the nitrogen cycle

Question 13

what is nitrogen fixation?

Answer 13

nitrogen gas reacts with hydrogen to form ammonia

Question 14

bacteria needed for nitrogen fixing?

Answer 14

Azotobacter and Rhizobium
contain the enzyme nitrogenase

Question 15

where is Azotobacter found?

Answer 15

found in the soil

Question 16

where is Rhizobium found?

Answer 16

found in the root nodules of a plant

Question 17

what is the relationship between Rhizobium and the plant called?

Answer 17

symbiotic mutualistic

Question 18

why is the relationship between Rhizobium and the plant mutualistic?

Answer 18

the bacteria fix nitrogen into ammonia which is taken up by the plant as amino acids
the plant produces carbs which are used by bacteria for energy

Question 19

what happens when soil is water logged?

Answer 19

no space for oxygen to reach bacteria in soil so aerobic respiration cannot take place

allows for denitrification…

Question 20

nitrogen cycle diagram

Answer 20