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GCSE biology > 4c + d - Human Impacts/Cycles > Flashcards

4c + d - Human Impacts/Cycles Flashcards

1
Q

What are the two ways nitrogen can be taken out of the air and converted?

A
  • nitrogen fixing bacteria

- lightning

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2
Q

Where is nitrogen fixing bacteria found?

A

In soil and in the root nodules of plants

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3
Q

How does a lightning convert nitrogen gas?

A

Splits the bond between the two atoms and turns them into nitrous oxide that dissolve in rainwater

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4
Q

Why do plants absorb the nitrates

A

To make proteins

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5
Q

How does the nitrogen go back into the soil?

A

As ammonium compounds in animal faeces

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6
Q

What does nitrifying bacteria do?

A

Converts the ammonium compounds to nitrites then to nitrates

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7
Q

What does denitrifying bacteria do?

A

Takes the nitrates out the soil and converts them back into nitrogen gas

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8
Q

Where is denitrifying bacteria found?

A

Poorly aerated soil

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9
Q

How can famers reduce unhelpful bacteria

A

Ploughing and turning over soil

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10
Q

Name 3 sources of water pollution?

A
  • toxic chemicals
  • untreated sewage
  • fertilisers
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11
Q

What’s the conditions for decomposition?

A

Warmth, moisture and air

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12
Q

What are detritus feeders’ role?

A

To start the decay process

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13
Q

What is eutrophication?

A

Water pollution caused by sewage or fertiliser

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14
Q

What is the effect of fertilisers in water?

A
  • causes increased plant growth (algal bloom)
  • which blocks sunlight so plants die
  • bacteria eats the dead plants using up o2
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15
Q

What is the effect of sewage in water?

A

provides food for bacteria which use up o2 therefore fish die

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16
Q

What pollutes the air?

A

Sulphur dioxide and nitrogen oxides

17
Q

How can acid rain effect plants?

A

damages leaves, buds, flowers and roots of trees

18
Q

How can acid rain effect fish?

A
  • Makes rivers too acidic

- causes leaching of toxic minerals eg aluminium

19
Q

What’s leaching?

A

The washing of chemicals into the soil or water by rain.

20
Q

What is a greenhouse gas?

A

A gas that absorbs infrared radiation from the sun

21
Q

What are the most important greenhouse gases?

A 
Water vapour
Carbon dioxide  
Methane 
Nitrous oxides 
CFCs
22
Q

How is carbon dioxide produced?

A

Combustion of fossil fuels

23
Q

How is methane produced?

A
  • by cattle
  • fermentation in rice fields
  • decomposition of waste In landfill sites
24
Q

What is the greenhouse effect?

A
  • sun emits rays to the earth
  • some heat bounces back to space
  • some heat is absorbed by green house gases
  • which is within earths atmosphere
25
Q

What is global warming?

A

An enhanced greenhouse effect

26
Q

What are the consequences of global warming?

A
  • decreases in biodiversity
  • loss of Habitats
  • ocean temperatures increase
27
Q

What are the effects of deforestation?

A
  • soil erosion
  • increased CO2 levels
  • flooding

GCSE biology (16 decks)

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