Nutrient Cycles Flashcards

1
Q

What is a nutrient cycle?

A

The process(es) by which certain nutrients pass through all three elements of the biosphere

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2
Q

What are the four main nutrient cycles?

A

Water
Oxygen
Nitrogen
Carbon

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3
Q

What is precipitation?

A

Any process which causes water to move from the atmosphere to the earth

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4
Q

What are examples of precipitation?

A
Rain
Snow
Fog
Hail
Dew
Frost
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5
Q

What is hygroscopic water?

A

The layer of water that adheres tightly around soil particles

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6
Q

What is capillary water?

A

Water that is found between soil particles

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7
Q

What kind of soil water is easily absorbed by plant roots?

A

Capillary water

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8
Q

What three things can happen to water that falls to the earth’s surface?

A

Absorbed by the upper layers of soil
Infiltration
Water run-off

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9
Q

What happens to water that is absorbed by the upper layers of soil?

A

Forms hygroscopic and capillary water

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10
Q

What is infiltration?

A

The process by which water is absorbed by the soil

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11
Q

What happens during infiltration?

A

Some water filters through the upper layers of soil to the water table

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12
Q

What is gravitational water?

A

The water that filters through to the water table

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13
Q

What occurs during water run-off?

A

Some of the water runs off above ground and forms streams and rivers

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14
Q

What do streams and rivers do?

A

They flow into lakes and oceans

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15
Q

What is the water table?

A

The upper surface of the saturated layer of groundwater

It is in the deeper layers of the soil

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16
Q

What are springs?

A

Groundwater that has reached the surface again

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17
Q

In what two ways can water reach the atmosphere?

A

Through evaporation

Through transpiration

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18
Q

What is evaporation?

A

The process whereby water particles les change to gas, but only on the surface of water (not boiling, can occur at any temperature)

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19
Q

How does transpiration allow water to enter the atmosphere?

A

When plants transpire they lose water to the atmosphere in the form of water vapour

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20
Q

What happens to water vapour in the atmosphere?

A

It condenses to form clouds

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21
Q

How would you summarise the water cycle?

A
Precipitation
Surface run-off, capillary water and infiltration
Springs (optional)
Evaporation and transpiration 
Condemnation
Precipitation
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22
Q

What are wetlands?

A

Semi-aquatic ecosystems

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23
Q

What sort of habitats are included in wetlands?

A

A wide range of inland and coastal habitats
Lagoons
Marshes
Estuaries

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24
Q

How are wetlands linked?

A

By rivers and streams

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25
Q

How do wetlands improve the environment?

A

Regular water supply
It is filtered naturally by vegetation
The effects of floods and droughts are reduced
They have a great biodiversity

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26
Q

What are some characteristics of wetlands?

A

They have a high water table
The soil has a high water-holding capacity
Hydrophytes are abundant

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27
Q

What are examples of plants that are commonly found in wetlands?

A

Bulrushes (Typha capensis)
Arum lily (Zantedeschia aethiopica)
Red-hot poker (Kniphofia caulescens)

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28
Q

What are the four main areas where oxygen occurs?

A

Atmosphere
Water masses
Rocks
Living organisms

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29
Q

What is the main source of oxygen on earth?

A

Photosynthetic organisms

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30
Q

What are photosynthetic organisms?

A

Plant life on land
Green algae
Phytoplankton

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31
Q

What substances are used and formed during photosynthesis?

A

Carbon dioxide

Carbohydrates and oxygen

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32
Q

What substances are used and formed during respiration?

A

Oxygen and carbohydrates

Carbon dioxide and water

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33
Q

Why do decomposers need oxygen?

A

They need it to break down organic matter and release CO2

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34
Q

How is oxygen responsible for surface weathering of rocks?

A

It combines with silicon (forms silicates) and iron (forms rust). These compounds then break away from the rocks

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35
Q

What does lichen do?

A

Break down rocks and release oxygen and nutrients for living organisms

36
Q

How is oxygen transferred from the atmosphere to the rocks?

A

Through surface weathering

37
Q

How is oxygen transferred from the rocks to living organisms?

A

Through weathering

38
Q

How is oxygen transferred from living organisms to water masses?

A

Photosynthesis

39
Q

How is oxygen transferred from water masses to living organisms?

A

Through respiration and decomposition

40
Q

How is oxygen transferred from living organisms to the atmosphere?

A

Through photosynthesis

41
Q

How is oxygen transferred from the atmosphere to living organisms?

A

Through respiration and decomposition

42
Q

Why is Nitrogen essential for living organisms?

A

They need it to form amino acids, which are the building blocks of proteins

43
Q

In what form is Nitrogen found in the atmosphere?

A

As “free” N2

44
Q

What is the only form of Nitrogen that plants can absorb?

A

Nitrates (NO3-)

45
Q

What are the two ways in which N2 is converted into NO3-?

A

Electrical fixation

Nitrogen-fixing bacteria

46
Q

What is electrical fixation?

A

It is when lightning and rain convert N2 into NO3- through a chemical reaction (induced by the heat of the lightning)

47
Q

What are the two types of nitrogen-fixing bacteria?

A

Free-living soil bacteria

Mutualistic nodule bacteria

48
Q

What are free-living soil bacteria?

A

Bacteria that exist in the spaces between soil particles

They absorb the Nitrogen in these spaces and convert it into NO3-

49
Q

What are mutualistic nodule bacteria?

A

Bacteria that live on the roots of legumes
They convert free Nitrogen into nitrates for the plant
In return, the plant provides food and a secure habitat for the bacteria

50
Q

What is assimilation?

A

The process whereby plant roots absorb Nitrogen in the form of nitrates

51
Q

What is Nitrogen used for in plants?

A

To form plant proteins

52
Q

How do animals obtain Nitrogen?

A

By eating the plants

53
Q

What happens to the Nitrogen in plants and animals when they die?

A

The proteins in their bodies are broken down into ammonia by decomposition bacteria

54
Q

What is ammonification?

A

The process whereby proteins are broken down into ammonia by decomposition bacteria

55
Q

What is another way in which Nitrogen becomes ammonia?

A

Through the excretion of urea by animals

This is then converted into ammonia (NH3)

56
Q

What happens to ammonia in the soil?

A

It is converted into nitrites by nitrifying bacteria

57
Q

What happens to nitrites in the soil?

A

It is converted to nitrates by nitrification by nitrifying bacteria

58
Q

What is nitrification?

A

The process whereby ammonia is converted into nitrates by nitrifying bacteria

59
Q

What two things can happen to nitrates in the soil?

A

Can be absorbed by plants

Can be converted into N2 by denitrifying bacteria

60
Q

What is denitrification?

A

The process whereby nitrates are converted to N2 by denitrifying bacteria

61
Q

Summarise the Nitrogen cycle, mentioning the origin, the destination, the process, the form in which Nitrogen is being transferred, and the cause at every step

A
  1. Atmosphere to soil, N2 to NO3-, fixation, lightning or bacteria
    2a. Soil to plant, NO3- to plant proteins, assimilation, plant roots
    2b. Soil to atmosphere, NO3- to N2, denitrification, denitrifying bacteria
    3a. Plants to animals, plant proteins to amino acids, eating, animals
    3b. Plant to dead organic material, plant proteins, death, cause varies
    4a. Animals to dead organic material, animal proteins, death, cause varies
    4b. Animals to ammonia, amino acids to urea to ammonia, excretion, metabolism
  2. Dead organic material to ammonia, proteins to NH3, decomposition, decomposition bacteria
  3. Ammonia to nitrites, NH3 to NO2-, nitrification, nitrifying bacteria
  4. Nitrites to nitrates, NO2- to NO3-, nitrification, nitrifying bacteria
62
Q

Why is carbon essential for life?

A

It is an important component of organic compounds: carbohydrates, proteins, lipids, nucleic acids and vitamins

63
Q

In what form does carbon occur in the atmosphere?

A

Carbon dioxide

CO2

64
Q

What are the five main places where carbon can be found?

A
Atmosphere
Plants 
Animals
Dead organic material
Fossil fuels
65
Q

How do plants obtain Carbon?

A

Through photosynthesis

66
Q

How do animals acquire carbon?

A

By eating plants

67
Q

How is carbon transferred to the soil?

A

When plants and animals die

68
Q

What can sometimes happen to dead organic material?

A

It can form fossil fuels

69
Q

How are fossil fuels formed?

A

Through fossilisation

70
Q

What happens during fossilisation?

A

Dead organic material is compressed to form fossil fuels

71
Q

What are examples of fossil fuels?

A

Coal

Oil

72
Q

How many ways are there for carbon dioxide to return to the atmosphere?

A

Three

73
Q

What are the three ways in which CO2 returns to the atmosphere?

A

Cellular respiration
Decomposition
Combustion

74
Q

How does cellular respiration cause CO2 to be released into the atmosphere?

A

During cellular respiration, organic compounds are broken down in the presence of oxygen and energy, water and CO2 are released

75
Q

How does decomposition cause CO2 to be released into the atmosphere?

A

Decomposers break down the organic compounds in dead plants and animals and release carbon in the form of CO2

76
Q

What is combustion?

A

Burning

77
Q

How does combustion cause CO2 to be released into the atmosphere?

A

Wood and fossil fuels release CO2 during combustion

78
Q

Summarise the carbon cycle, stating origin, destination and the process by which it is transferred

A

Atmosphere to plants through photosynthesis
Plants to atmosphere through respiration and combustion
Plants to animals through eating
Animals to atmosphere through respiration
Plants and animals to dead organic matter through death
Dead organic matter to atmosphere through decomposition
Dead organic matter to fossil fuels through fossilisation
Fossil fuels to atmosphere through combustion

79
Q

What happens when nutrient cycles do not function correctly?

A

It leads to negative consequences

80
Q

Give an example of a negative consequence caused by a nutrient cycle imbalance

A

Climate change

81
Q

How is climate change causes by a nutrient cycle imbalance?

A

Too many greenhouse gases (incl. carbon dioxide) in the atmosphere

82
Q

Why is an excess of greenhouse gases a bad thing?

A

They trap the heat of the earth’s atmosphere and cause the earth’s temperature to rise

83
Q

What has caused this carbon cycle imbalance?

A

Human activities

84
Q

What human activities have caused this carbon cycle imbalance?

A

The burning of fossil fuels has increased the amount of CO2 in the atmosphere
Deforestation has decreased photosynthesis

85
Q

What are some possible solutions to the carbon cycle imbalance?

A

Reduce the use of fossil fuels
Control industrial gas emissions
Cooperation to reduce the release of greenhouse gases

86
Q

How do you reduce the use of fossil fuels?

A

By using alternative energy sources

87
Q

Give some examples of alternative energy sources

A

Solar energy
Wave energy
Wind energy