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Edexcel GCSE Biology Higher > Topic 9 - Ecosystems And Material Cycles > Flashcards

Topic 9 - Ecosystems And Material Cycles Flashcards

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1
Q

Symbiosis

A

The ecological relationship between organisms living closely together with some form of feeding relationship involved

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2
Q

Mutualism

A

Where both organisms benefit e.g Bumble Bee and Pollinating Flower

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3
Q

Commensalism

A

Where one organism benefits while the other organism is not harmed e.g Cattle Egrets and Livestock

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4
Q

Parasitism

A

Where one organism benefits and causes harm to the other organism e.g Endoparasites and Ectoparasites

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5
Q

Examples of endoparasites

A

Tapeworms, Roundworms that live in the digestive systems of its host

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6
Q

Examples of ectoparasites

A

Lice, ticks, fleas

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7
Q

Community

A

Populations of different species that live and interact with each other.

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8
Q

Ecosystem

A

A community of organisms and the physical environment they live in.

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9
Q

Habitat

A

The place in which an organism lives.

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10
Q

Population

A

All the organisms of a particular species living in the same area.

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11
Q

Interdependent

A

When organisms in an area depend on each other for resources to survive.

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12
Q

What resources do plants need?

A

Oxygen, water, light, carbon dioxide, warmth, minerals

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13
Q

What resources do animals need?

A

Food, water, oxygen

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14
Q

What resources do plants and animals both need?

A

Water and oxygen

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15
Q

Food web definition -

A

Shows feeding relationships between organisms of a community.

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16
Q

Food chain definition -

A

Shows where the energy is transferred in a food chain

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17
Q

A pyramid of numbers -

A

Shows how many animals or organisms we’re talking about.

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18
Q

A pyramid of biomass -

A

Shows how much the creatures at each level would weigh.

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19
Q

Main ways energy is lost -

A
  • Through waste minerals
  • Through living processes such as movement or growth. This energy is supplied by respiration.
  • Keeping the body at its correct temperature (body heat is always lost to the surroundings).
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20
Q

How to improve the efficiency of a food chain -

A
  • Reduce the number of stages
  • Limit an animal’s movement
  • Keep it warm
  • Use plant hormones to regulate the ripening of fruit
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21
Q

Abiotic factors -

A

Non living factors that impact the distribution of organisms e.g temperature, water availability, light availability, pollution

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22
Q

Biotic factors

A

Are living factors that impact the community e.g predation and competition

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23
Q

Competition meaning

A

Fighting over resources to survive such as food, water and shelter

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24
Q

Limited resource

A

Resources that are not unlimited in an ecosystem so they run out like water

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25
Q

What is nitrogen used for in living organisms?

A

Used to make proteins and DNA.

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26
Q

Although the atmosphere is 80% Nitrogen, it cannot be used directly because it is so…

A

Unreactive

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27
Q

How do organisms access Nitrogen if not directly from the atmosphere?

A

Microorganisms play a key role in the cycling of nitrogen in different compounds and converting it from one form to another.

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28
Q

Role of Nitrogen-Fixing Bacteria

A

Converts Nitrogen Gas into nitrates

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29
Q

Role of de-nitrifying bacteria

A

Breaks down nitrates in the soil, releasing nitrogen gas back into the air

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30
Q

Role of decomposer (nitrifying) bacteria

A

Breaks down the proteins in dead organisms, releasing nitrates back into the soil.

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31
Q

What is in nodules on the roots of peas and clover?

A

Nitrogen-fixing bacteria

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32
Q

What fertiliser do farmers put on grass to improve leaf growth?

A

NPK Fertiliser

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33
Q

How do plants take up nitrates?

A

From the soil through their roots by active transport

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34
Q

How do plants obtain nitrogen?

A

From nitrates in the soil

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35
Q

5 ways in which nitrogen is added to the soil:

A
  • Lightning
  • Nitrogen-fixing bacteria in root nodules
  • Nitrogen-fixing bacteria in soil
  • Nitrifying bacteria breaking down dead animals and plants
  • Nitrifying bacteria breaking down waste materials from animals
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36
Q

Describe the roles of bacteria in the nitrogen cycle (4 marks)

A
  • decomposers break down waste matter (into ammonia) (1)
  • nitrifying bacteria convert ammonia / nitrifying bacteria make {nitrites / nitrates} (1)
  • nitrogen fixing bacteria convert nitrogen into nitrates (1)
  • denitrifying bacteria {convert nitrates / release nitrogen) (1)
37
Q

Eutrophication definition and example

A

Is when lots of nutrients are added to the environment e.g when a farmer spreads fertiliser on crops

38
Q

Why does a farmer spray fertiliser on crops?

A

It contains nutrients that help the crop plants grow well.

39
Q

Where does the fertiliser come from?

A

It is artificial or natural.

40
Q

Why is preserving biodiversity important?

A
  • Conserving individual species
  • Means areas recover faster from naturally disasters
  • Animals and plants for food and medicines
41
Q

What is conservation?

A
  • When an effort is made to protect a rare or endangered species or habitat.
42
Q

Reforestation effects

A

Preserves habitats
Increased biodiversity
Conservation of rare species

43
Q

Examples of abiotic factors in a landscape

A
  • Light intensity
  • Water availability
  • Wind Speed
  • Soil nutrient availability
44
Q

Explain how reforestation of hills can help to reduce flooding in river valleys.

A
  • Planted trees absorb more rainwater.
  • Therefore, less water will run off into streams and rivers, reducing flooding in the river valleys.
45
Q

How farmers get it wrong - eutrophication:

A
  • Too much nitrate fertiliser
  • Apply nitrate fertiliser just before rain
  • Gives farmers a bad image as environment spoilers
46
Q

Explain how water from fields sprayed with fertiliser can affect the growth of algae and plants in the stream or river.

A

The water contains lots of nutrients that the algae and plants can use to grow faster.

47
Q

Describe the effect that lots of floating plants and algae will have below the water surface.

A

The amount of light reaching deeper into the water will be greatly reduced.

48
Q

Describe the effect that the reduced light will have.

A

Lack of light will prevent plants below the water surface from photosynthesising. So those plants will die.

49
Q

What will the bacteria need so they can carry out aerobic respiration?

A

oxygen from the water

50
Q

What effect will reducing oxygen in the water have on other organisms?

A

They may not be able to get enough oxygen for respiration, and will die.

51
Q

Fish farming - definition

A

Fish farmed in large nets (an enclosed space) or tanks within lakes or in the sea.

52
Q

Pro of fish farming

A

Numbers increase quickly

53
Q

Cons of fish farming -

A

▪ Too many fish kept in a small space,
so parasites and disease spreads more
easily
▪ Uneaten food and faeces sink to the
bottom of the water, which may
change the conditions and harm the wild organisms that live there.

54
Q

How is water safe to drink?

A
  • Freshwater from rivers/lakes/reservoirs must be treated with chemicals and filtered to remove dirt, pathogens and toxic substances.
  • This may also improve the taste, by removing other non-toxic substances.
55
Q

How is water collected in areas of drought?

A
  • From the air or extracted from sea water
56
Q

Desalination -

A
  • Obtaining fresh water from sea water.
  • Distillation can be used to achieve this.
57
Q

What does the water cycle do?

A
  • Moves water and nutrients through the atmosphere, soil, rivers and oceans.
  • This helps to replenish those which have been used within a habitat.
58
Q

In what form is carbon in the atmosphere?

A

Carbon Dioxide gas (CO2)

59
Q

Which process in living organisms removes carbon dioxide from the atmosphere?

A

Photosynthesis

60
Q

Which molecule containing carbon is formed during photosynthesis?

A

C6H12O6 - Glucose

61
Q

Plants use the glucose from photosynthesis for energy and to make other compounds. Name three of these compounds.

A

Cellulose, protein, starch

62
Q

Which form of carbon is produced by the combustion of fossil fuels?

A

Carbon Dioxide

63
Q

Which group of organisms breaks down the complex carbon atoms in dead tissue?

A

Decomposers

64
Q

What is the role of decomposers in the carbon cycle?

A
  • Break down dead organisms
  • Return the carbon in their bodies to the atmosphere as carbon dioxide by respiration.
65
Q

What are quadrats used for?

A
  • Sampling plants.
66
Q

How do quadrats have to be placed?

A
  • Randomly by using random numbers to create co-ordinates.
67
Q

Number of an individual species (population size):

A

The total number of individuals of one species (e.g daisies) is recorded.

68
Q

Species richness:

A
  • The number of different plant or animal species is recorded but not the number of individuals within a species.
69
Q

Percentage Cover definition:

A
  • Percentage of the quadrat area covered by one species.
  • This is easier to estimate if the quadrat has wires making smaller sections.
70
Q

When is percentage cover used?

A
  • It is used when estimating plant frequencies if it is difficult to identify individual plants, such as grasses or moss.
71
Q

Calculating Population Size

A
  • = Number Of Organisms in all Quadrats * (Total Size where organism lives / total area of quadrats)
72
Q

Random Sampling -

A
  • Used to sample a large area, usually to estimate population size in a habitat.
  • Can be used to compare populations in two different areas.
73
Q

Transect -

A
  • Used to investigate a gradual change in a habitat.
  • A line across a habitat or part of a habitat is sampled, with the number of organisms being recorded at regular intervals.
74
Q

What are indicator species?

A
  • Species that can indicate the presence, absence or abundance of a specific environmental condition.
75
Q

What is air pollution caused by?

A
  • The combustion of fossil fuels in vehicle engines and power stations.
  • Sulphur dioxide is released if the fuel
    contains sulphur compounds.
76
Q

Water Pollution - what is it caused by?

A
  • Poisonous substances released by factories, such as mercury and detergents.
  • Also, from fertilisers which can cause eutrophication.
77
Q

How can water pollution be indicated?

A
  • Sludgeworm = extreme
  • Bloodworm = high
  • Freshwater shrimp = slight
  • Stonefly nymph = low (stream)
78
Q

How can air pollution be indicated? Lichens:

A
  • Lichens are mutualistic relationships between
    fungus and algae.
  • Different species of lichens need different air qualities to grow. In areas with crusty or no lichens, the air pollution is high or very high. In areas with larger, bushier lichens, the air pollution is lower.
79
Q

How can air and water pollution both be measured?

A
  • Air and Water pollution can also be measured using sensors.
  • These give numerical data at the time of measuring.
  • Indicator species do not give as much detail, but they are useful as a simple assessment of long-term health of ecosystems.
80
Q

Composting -

A
  • Gardeners and farmers will collect waste garden material into heaps and keep it until it is well-decayed and has formed compost.
  • Compost contains many nutrients, that were stored in the waste, but inaccessible until decomposition had occurred.
  • Compost can increase soil fertility.
81
Q

Calculating Rate of Decay -

A

Rate of Decomposition = Mass Lost / Number of Days

82
Q

Reducing temperatures using freezers and fridges to preserve food -

A
  • The lower the temperature, the slower the rate of reactions that take place inside living cells.
  • This includes the reactions that cause decomposition of food.
83
Q

Reducing water content by drying meat to preserve food -

A
  • Removes water that decomposers need for rapid growth.
84
Q

Adding Salt or Sugar to preserve food -

A
  • A high solute concentration draws water out of the cells of decomposer organisms by osmosis, which can kill them.
85
Q

Irradiation of packaged foods to preserve food -

A
  • Kills decomposers.
86
Q

Storing foods in oil, packaging in unreactive nitrogen gas, vacuum packing, or in cans to preserve food -

A
  • reduces/removes oxygen needed for aerobic respiration.
87
Q

Pickled with vinegar to preserve food -

A
  • pH affects enzymes that control the rate of reactions.
  • If the pH of the food is reduced, this can slow down
    the decomposition reactions caused by decomposer organisms.
88
Q

Air pollution - Blackspots:

A
  • Blackspot is a fungus that infects roses.
  • It cannot grow well where there is lots of sulfur pollution. So, roses in city areas rarely experience the blackspot fungus.

Edexcel GCSE Biology Higher (11 decks)

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