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Biology igcse > 4A,B,C,D Ecology & the Environment > Flashcards

4A,B,C,D Ecology & the Environment Flashcards

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1
Q

Define the term population

A

A group of organisms of the same species in an area

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2
Q

Define the term community

A

A group of organisms of different species in an area

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3
Q

Define the term ecosystem

A

The organisms + the environment

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4
Q

Define the term habitat

A

A place where an organism lives

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5
Q

TRIPLE ONLY
Define the term biodiversity

A

The variety of genes, species and habitats

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6
Q

Describe the difference between biotic and abiotic factors

A

Biotic = living factors

Abiotic = non-living factors

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7
Q

Give 3 examples of biotic factors

A

Predation

Competition

Disease

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8
Q

Give 3 examples of abiotic factors

A

Light intensity

Temperature

Humidity

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9
Q

What does the term abundance mean

A

The number of organisms

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10
Q

Describe how to estimate the population size of an organism in an area using a quadrat

A

Randomly lay quadrat
ID organisms using a key
Count number of individuals
Record abiotic factors e.g. …?
Repeat several times
Calculate mean and then times by total area

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11
Q

Explain how to avoid bias when sampling in biology

A

Randomly place quadrat

(i.e. use random number generator to get coordinates for placement)

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12
Q

Explain how to increase reliability when sampling

A

Increase sample size - place more quadrats down

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13
Q

TRIPLE ONLY
What does the term distribution mean in biology

A

Where organisms are located

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14
Q

TRIPLE ONLY
State what piece of equipment you would use to measure how the distribution of organisms change from one area to another

A

Line transact

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15
Q

TRIPLE ONLY
Describe how you would measure how the distribution of an organism changes

A

Lay line transect from one area to another (must be specific where)
Place quadrat at even intervals along transect (e.g. every 5m)
ID organisms using a key
Count number of individuals
Record abiotic factors e.g…?
Repeat line transect several times

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16
Q

Define the term trophic level

A

Stage in a food chain

17
Q

Define these food chain terms:
Producer
Consumer
Decomposer

A

Producer = makes own food using photosynthesis

Consumer = needs to eat other organisms to get nutrition

Decomposer = breaks down decaying matter to get nutrition

18
Q

What do all food chains start with, and give common examples

A

All start with producers e.g. plants, algae

19
Q

How much energy is transferred from one stage in a food chain (trophic level) to another

A

Just 10%

20
Q

Explain why energy is lost as you move along food chains

A

Energy released for heat, movement, release of faeces

Not all parts of organisms are eaten either e.g. bark of trees

21
Q

Describe how carbon is released into the atmosphere during the carbon cycle

A

Combustion of fuels

Respiration of plants, animals, decomposers

Volcanic activity

22
Q

Describe how carbon is absorbed from the atmosphere in the carbon cycle

A

Photosynthesis

Dissolving in oceans

23
Q

TRIPLE ONLY
State the role of nitrogen-fixing bacteria in the nitrogen cycle

A

Turns atmospheric nitrogen (N2) into nitrogen compounds in soil and plants

24
Q

TRIPLE ONLY
State the role of decomposers in the nitrogen cycle

A

Break down large nitrogen compounds into ammonium compounds

25
Q

TRIPLE ONLY
State the role of nitrifying bacteria in the nitrogen cycle

A

Convert ammonia into nitrites and nitrates

26
Q

TRIPLE ONLY
State the role of denitrifying bacteria in the nitrogen cycle

A

Converts nitrates back into atmospheric nitrogen (N2)

27
Q

TRIPLE ONLY
Explain the role of lightning in the nitrogen cycle

A

Atmospheric nitrogen (N2) reacts with oxygen in the air to form nitrates in the soil

28
Q

TRIPLE ONLY
Explain why it is important for atmospheric N2 to be fixed into nitrogen compounds for organisms to use

A

Used to make amino acids and DNA

29
Q

State two main pollutant gases

A

Sulphur dioxide (SO2)

Carbon monoxide (CO)

30
Q

State the biological consequences of sulfur dioxide

A

Forms acid rain - dissolves leaves and makes lakes acidic, killing fish

31
Q

State the biological consequences of carbon monoxide

A

Binds to haemoglobin

Less oxygen transported to cells, so less respiration

Leads to fatigue, dizziness and can lead to death

32
Q

State 5 greenhouse gases

A

Methane

Carbon dioxide

Water vapour

Nitrous oxides

CFCs

33
Q

Explain what is meant by a greenhouse gas

A

Traps heat in the earth’s atmosphere

34
Q

List the activities that have increased the number of greenhouse gases in the atmosphere

A

Burning fossil fuels

Cutting down trees

Increased cars, factories etc

Cattle farming and rice fields (releases methane)

35
Q

Explain the main effects that too many greenhouse gases can have on the planet

A

Climate change and extreme weather

Desertification

Ice caps melting, causes sea level rise and flooding

Affecting animal migrations

36
Q

Explain why sewage in waterways can kill aquatic life i.e. fish

A

Sewage provides nutrients for bacteria to grow

Bacteria grow, respire and use up oxygen in water

No more oxygen in water kills fish (water becomes anoxic)

37
Q

Describe the process of eutrophication

A

Fertiliser/nutrients flow into water i.e. pond
Algae on surface grow
Algae block sunlight for underwater plants
Plants die (cannot photosynthesise)
Bacteria feed on plants and respire, using up oxygen in water
No oxygen kills fish

38
Q

Explain what leaching is

A

Fertilisers dissolve in rainwater and drains into rivers, ponds and lakes

39
Q

TRIPLE ONLY
Describe 4 effects of deforestation on the environment

A

Leaching → mineral ions aren’t taken up by roots so wash away in rainwater

Soil erosion → no roots to stabilise soil, leads to land slides

Evapotranspiration → less trees to recycle water vapour by transpiration

Carbon dioxide → less trees means less photosynthesis so less carbon dioxide absorbed from atmosphere

Biology igcse (6 decks)

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