Nitrogen Cycle Flashcards

1
Q

What process converts N2 into NH4+?

A

nitrogen fixation

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2
Q

What are 2 examples of anaerobic conditions?

A
  • very compact soil
  • water-logged soil
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3
Q

Draw the nitrogen cycle

A

use book

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4
Q

How are plants involved in the nitrogen cycle?

A

they assimilate NO3 (using it in proteins, DNA, RNA etc.)
their nitrogen containing compounds are broken down by saprobionts

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5
Q

How can lightning be involved in the nitrogen cycle?

A

it can break the bond between N2, allowing nitrogen to react with oxygen and form nitrates, without the need for bacteria

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6
Q

How are nitrate ions taken up by roots?

A

active transport

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7
Q

What are the 4 main stages in the nitrogen cycle?

A
  • nitrogen fixation
  • nitrification
  • ammonification
  • denitrification
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8
Q

What is ammonification?

A

production of ammonia from nitrogen containing compounds (eg urea, proteins and nucleic acids) found in waste and dead organisms

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9
Q

What do ammonifying bacteria do?

A

convert nitrites into ammonia

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10
Q

What microorganisms carry out ammonification?

A

saprobionts

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11
Q

What is nitrification?

A

the oxidation reaction converting ammonium ions into nitrate ions

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12
Q

What microorganisms carry out nitrification?

A

nitrifying bacteria

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13
Q

What is required for nitrifying bacteria to carry out nitrification?

A

oxygen (aerated soil)

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14
Q

What is nitrogen fixation?

A

the process converting atmospheric nitrogen into ammonia and ammonium ions

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15
Q

What are the types of nitrogen fixing bacteria?

A

free-living and mutualistic

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16
Q

What are free-living nitrogen fixing bacteria?

A
  • live in soil
  • convert nitrogen to ammonia and use this to form amino acids and nitrogen containing compounds which are released when they die
17
Q

What are mutualistic nitrogen fixing bacteria?

A
  • live on nodules of roots (of leguminous plants)
  • form ammonia from nitrogen and use this to make a/a
18
Q

Why are mutualistic nitrogen-fixing beneficial to the plant? What do they benefit from?

A
  • plants obtain amino acids
  • bacteria obtain carbohydrates
19
Q

What is denitrification?

A

nitrates in soil are converted to atmospheric nitrogen

20
Q

What microorganism carries out denitrification?

A

anaerobic denitrifying bacteria