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GCSE Biology > Topic 9: Ecosystems and Material Cycles > Flashcards

Topic 9: Ecosystems and Material Cycles Flashcards

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1
Q

What are the three types of nutrients cycle?

A

Carbon, water and nitrogen cycle

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2
Q

Why are the nutrients cycles important?

A

Carbon, water and nitrogen are essential to life and there is a fixed amount of nutrients on Earth which must be constantly recycled

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3
Q

How are materials cycle going though the living and non-living components of an ecosystem?

A

Organisms take in elements from their surroundings, elements converted to complex molecules which become biomass, elements transferred along food chain and elements returned to environment during excretion and decomposition of dead organisms

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4
Q

What are the stages of the carbon cycle?

A

Photosynthesis plants remove CO2 from the atmosphere, eating passes carbon compounds along the food chain, respiration in plants plants and animals returns CO2 to the atmosphere, organisms die and decompose, decomposers break down dead material and release CO2 via respiration and combustion of materials releases CO2

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5
Q

What are the stages of the water cycle?

A

Energy from the sun evaporates water from sources, transpiration also releases water vapour, water vapour rises, cools and condenses forming clouds, precipitation occurs, water is absorbed by the soil and taken up by roots, some is used in photosynthesis or becomes part of the plant, entering the food chain, excretion returns water to the soil and surface runoff returns to streams, rivers and eventually the sea

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6
Q

What is potable water?

A

Drinking water

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7
Q

How can potable water be prepared?

A

Desalination

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8
Q

What is desalination?

A

A process that removes salts from saline water

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9
Q

What are two methods of desalination?

A

Thermal desalination and reverse osmosis

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10
Q

What is thermal desalination?

A

Salt water is boiled, water evaporates, rises and condenses down a pipe and this separates pure water from salts

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11
Q

What happens is reverse osmosis?

A

Saline water pumped into a vessel containing a partially permeable membrane at high pressure, high pressure forces water molecules to move from an area of low water concentration to an area of high water concentration and pure water separated from salts

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12
Q

What do plants use to make proteins?

A

Nitrates

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13
Q

Why can’t nitrogen be used directly by plants to form proteins?

A

Nitrogen is unreactive

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14
Q

What are the four types of bacteria involved in the nitrogen cycle?

A

Decomposers, nitrogen-fixing bacteria, nitrifying bacteria and denitrifying bacteria

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15
Q

What is the role of decomposers in the nitrogen cycle?

A

Break down proteins and urea into ammonia and ammonia dissolves in solution forming ammonium ions

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16
Q

What is the role of nitrogen-fixing bacteria in the nitrogen cycle?

A

Convert nitrogen gas into ammonia and ammonia dissolves in solution forming ammonium ions

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17
Q

Where are nitrogen-fixing bacteria found?

A

Soil and root nodules of legumes

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18
Q

What type of relationships is exhibited between nitrogen-fixing bacteria and legumes?

A

Mutualistic relationship, plants receive ammonium ions from bacteria and bacteria gain sugars from the plants

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19
Q

What is the role of nitrifying bacteria in the nitrogen cycle?

A

Convert ammonium ions into nitrites and convert nitrites into nitrates

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20
Q

What is the role of denitrifying bacteria in the nitrogen cycle?

A

Convert nitrates into nitrogen gas

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21
Q

Where are denitrifying bacteria commonly found?

A

Waterlogged soils

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22
Q

What are the stages of the nitrogen cycle?

A

Lightning and nitrogen-fixing bacteria convert nitrogen gas to ammonia which dissolves to form ammonium ions, nitrifying bacteria convert ammonium ions to nitrate ions which are taken up by plants and used to build protein, feeding passes nitrogen through the food chain, organisms die and decompose, decomposers break down proteins and urea to form ammonia which dissolves to form ammonium ions and denitrifying bacteria convert nitrates in the soil back into nitrogen gas

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23
Q

How can the amount of nitrate in the soil be increased?

A

Using fertiliser and crop rotation replenishes nitrates that may have been depleted by the previous crop

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24
Q

What is decomposition?

A

The breakdown of dead materials into simpler organic matter

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25
Q

How do decomposers break down dead matter?

A

Decomposers release enzymes which catalyse the breakdown of dead material into smaller molecules

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26
Q

What factors affect the rate of decomposition?

A

Oxygen availability, temperature and water content

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27
Q

Why is oxygen required for decomposition?

A

Most decomposers require oxygen for aerobic respiration

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28
Q

How does the availability of oxygen affect the rate of decomposition?

A

As oxygen levels increase, the rate of decomposition increases but as oxygen levels decrease, the rate of decomposition decreases

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29
Q

Why can decomposition still occur in the absence of oxygen?

A

Some decomposers respire anaerobically but the rate is slower and produces less energy

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30
Q

How does temperature affect the rate of decomposition?

A

Decomposers release enzymes: rate highest at 50C, lower temperatures, enzymes work too slowly, rate decreases and high temperatures, enzymes denature and decomposition stops

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31
Q

How does soil water content affect the rate of decomposition?

A

Decomposers require water to survive: in moist conditions the rate of decomposition is high and in waterlogged soils there is little oxygen for respiration so the rate of decomposition decreases

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32
Q

What conditions are required to make compost?

A

Conditions that give a high rate of decomposition: plentiful supply of oxygen, warm and moist

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33
Q

What is the methods of food store used to slow down the rate of decomposition?

A

Stored in fridge/freezer to slow down the activity of microbes, stored in airtight cans to prevent the entry of microorganisms, high temperatures sterilised cans, destroyed any bacteria, adding salt or sugar kills microbes and food kept dry to reduce the ability of microorganisms to survive

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34
Q

What is an indicator species?

A

A species whose presence or absence in an environment provides indication of environmental conditions

35
Q

What indicator species can be used to identify polluted water?

A

Bloodworms and sludge-worms

36
Q

What indicator species can be used to identify clean water?

A

Freshwater shrimps and stonefly

37
Q

What indicator species can be used to identify clean air?

A

Black spot fungus found on rose leaves

38
Q

What are lichens used for?

A

Used to monitor air pollution

39
Q

How can lichens indicate air pollution?

A

Sensitive to the concentration of soulful dioxide, different types of lichens grow in different levels of air pollution, abundance and distribution of lichens indicate levels of pollution

40
Q

What are the use of indicator species as a measure of pollution?

A

Cheaper, simpler and used to monitor pollution levels over a long periods of time however less accurate than non-living indicators and don’t provide a definitive figure of pollution levels

41
Q

What the levels of organisation in an ecosystem?

A

Individual, population, community and ecosystem

42
Q

What is population?

A

All organisms of the same species living with one another in a habitat

43
Q

What is community?

A

All of the populations of different species living together in a habitat

44
Q

What is ecosystem?

A

The community of organisms and non-living components of an area and their interactions

45
Q

What does ‘organisms within a community are described as being ‘interdependent’ mean?

A

Organisms are dependent upon each other and a change in the population of one species can affect other populations within a community

46
Q

What are some examples of interdependent in a community?

A

Plants depend on pollination, herbivores are dependent on plants and animals are dependent on mares

47
Q

What is mutualism?

A

The interaction between two organisms where both benefit as a result of their relationship

48
Q

What is the parasitism?

A

The interaction between two organisms where only one organism, the parasite, benefits whilst the host doesn’t

49
Q

What are abiotic factors?

A

The non-living aspects of an ecosystem e.g temperature and light intensity

50
Q

How does communities are affected by environmental conditions?

A

Environmental conditions affect the abundance and distribution of organisms within communities

51
Q

How are communities affected by pollutants?

A

Toxic chemicals bioaccumulate in food chains to deadly concentrations at higher trophic levels, killing tertiary and quaternary consumers, fertilisers that contaminate water sources can cause eutrophication, killing multiple populations within a community and air pollution can affect the ability of some plant’s species to survive

52
Q

What are biotic factors?

A

The living components of an ecosystem e.g competition

53
Q

How does competition affects communities?

A

The presence of competitors affects population distribution and size and if one species is better adapted to survive in a certain environment, it will outcompete other species, causing their populations to decline

54
Q

How does predation affects communities?

A

predation affects prey populations within a community and population of all other organisms within the food chain will also be affected

55
Q

What piece of apparatus is used to measure the abundance and distribution of organisms in an area?

A

Quadrat

56
Q

Which piece of apparatus is used to study the distribution of organisms across a gradient?

A

Belt transect

57
Q

What does a food chain show ?

A

It describes the feeding relationships between organisms and the resultant stages of biomass transfer

58
Q

What is biomass?

A

The total mass of living material

59
Q

What are trophic levels?

A

The stages in a food chain

60
Q

What do arrows in a food chain represent?

A

The direction of biomass transfer

61
Q

What is a simple food chain?

A

Producer -> primary consumer -> secondary consumer-> tertiary consumer

62
Q

Why are producers the first trophic levels?

A

Producers provide all biomass for the food chain and the rest of the food chain involves the transfer of this biomass

63
Q

What does a pyramid of biomass represent?

A

It represents the dry mass of living material at each trophic level of a food chain

64
Q

Why is a pyramid of biomass almost always pyramid-shaped?

A

Producers have the greatest biomass so have the longest bar and as you move along the food chain biomass is lost so the bars decrease in length

65
Q

Why is biomass lost between each trophic level in a food chain?

A

Glucose is immediately used for respiration in plant, respiration to generate heat energy for movement, some parts of organisms are indigestible and egestion and excretion

66
Q

Why are there rarely more than four or five trophic levels in a food chain?

A

Above this, there is insufficient energy to support another breeding population

67
Q

What is the equation for calculating the efficiency of biomass transfer between trophic levels?

A

Biomass available after transfer / biomass available before transfer x 100

68
Q

What is biodiversity?

A

The variety of living organisms in an ecosystem

69
Q

How does fish farming farming affect biodiversity?

A

Food used to feed the fish and waste can leak into water sources, causing eutrophication, parasites from fish farms may spread and contaminate surrounding ecosystems and other organisms may become tangled in netting

70
Q

How does the use of fertilisers affect biodiversity ?

A

Excess fertiliser can wash into water sources causing eutrophication and death of many species so this reduces biodiversity

71
Q

How can fertilisers cause eutrophication?

A

Fertilisers run-off into rivers and lakes, nutrients build-up in water, algal bloom blocks sunlight, aquatic plants cannot photosynthesise, less oxygen produced, they die and decompose, decomposers further depleted oxygen levels and animals can no longer respire aerobically so die

72
Q

How does the introduction of non-indigenous species affect biodiversity?

A

They may out-compete native species, causing a reduction in population numbers, native species may become the prey of no-indigenous species and they may bring new diseases which could kill large numbers of native species, reducing biodiversity

73
Q

How can humans more positively impact biodiversity?

A

Protection of endangered species, conservation schemes, reforestation, sustainable farming and minimising global greenhouse gas production

74
Q

What is reforestation?

A

Replanting forests to help restore biodiversity

75
Q

How do conservation schemes protect biodiversity?

A

They prevent species from becoming extinct and increase’s populations numbers, maintaining biodiversity

76
Q

What are the benefits of maintaining biodiversity?

A

Ensures future food requirements can be met, reduces damage to food chains, increases the likelihood of species adapting to future environmental change, many plant species are yet to be discovered and may contain chemicals that could be used in future medicines, safeguarding valuable future resources, aesthetics and jobs provided by ecotourism, reforestation and conservation schemes

77
Q

What is food security?

A

Ensuring that populations have access to adequate amounts of safe and nutritious foods

78
Q

What are some of the biological factors affecting food security?

A

Rising human population, changing diets, new pests and pathogens, environmental change and sustainability

79
Q

How can the rising human population affect food security?

A

As human population increases, global food production must also increase in order to meet the growing demand for food

80
Q

How can changing diets affects food security?

A

Greater consumptions of near and fish in wealthier populations, less energy and biomass available from livestock than crops, livestock use land for grazing and are fed crops that could otherwise be uses for human consumption and less food is available for humans and reduction in food security

81
Q

How can new pests and pathogens affect food security?

A

Pests and pathogens can reduce or destroy crop yields, negatively impacting food security

82
Q

How can sustainability affects food security?

A

Unsustainable farming methods disrupt food chains, compromising the ability to meet future food requirements, due to the high input costs, many LEDCs cannot maintain modern farming methods and using land for biofuel production reduces land available for crops

83
Q

How can environmental change due to human activity affects food security?

A

Emissions of greenhouse gases have been linked to global warming which must affect crop growth and salinisation reduce agricultural potential of soils

GCSE Biology (9 decks)

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