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Biology GCSE > Ecology and the Environment > Flashcards

Ecology and the Environment Flashcards

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1
Q

Explain the greenhouse effect

A

1) the temperature of the Earth is a balance between the heat it gets from the Sun and the heat it radiates back to space
2) gases in the atmosphere (greenhouse gases) absorb most of the heat that would otherwise be radiated back to space, and re-radiate it back towards the Earth
3) if this didn’t happen, then at night there’d be nothing to keep any heat in and the Earth would be very cold

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2
Q

What are the effects of deforestation?

A

Leaching
Soil erosion
Disturbing the water cycle
Disturbing the balance of carbon dioxide and oxygen

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3
Q

What are decomposers?

A

These decay dead material to help to recycle nutrients.

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4
Q

How do animals get their nitrogen to make proteins?

A

By eating plants or each other

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5
Q

How do you do a random sample?

A
  1. Lay down two tape measures to form a grid.
  2. Get random co-ordinates to determine the point on the grid where the sample should be taken. This removes bias.
    3 place down the quadrat and count all the organisms within the quadrat.
  3. Multiply the number of organisms by the total area of the habitat.
  4. Repeat in another area and compare population sizes.
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6
Q

How do quadrats work

A

The size of a quadrat hard will depend on the plant community being recorded.
These mark out an area for sampling.
Plants and animals are recorded by counting the number or estimating percentage cover.

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7
Q

Explain how the balance of carbon dioxide is disturbed as an effect of deforestation

A

Forests take up CO2 by photosynthesis, store it in wood, and slowly release it when they decompose as microorganisms feeding on dead wood releases CO2 as a waste product of respiration
When trees are cut down and burnt, the stored carbon is released very rapidly as CO2 - this contributes to global warming

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8
Q

What is random sampling?

A

Not interested in recording the pattern of species in an area (for one variable e.g. Light intensity or estimating population size).

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9
Q

What shape are pyramids of energy transfer?

A

They are always pyramid shaped.

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10
Q

What is a food chain?

A

A feeding heirarchy of organisms in an ecosystem to represent to flow of food energy and the feeding relationships.

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11
Q

How is carbon monoxide produced and released?

A

When fossil fuels are burnt without enough air supply they produce the gas carbon monoxide
CO is mostly released in car emissions

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12
Q

What are the stages of a food chain?

A

Producer

Primary consumer

Secondary consumer

Tertiary consumer (top carnivore)

Each stage is a trophic level.
All these organisms eventually die and get eaten by decomposers, e.g. Bacteria.

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13
Q

How does human activity contribute to global warming by releasing CFCs

A

It used to be used in fridges and aerosol sprays, which released them - but these are mostly not produced anymore
But some CFCs remain and get released e.g. by leaks from old fridges

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14
Q

What are the types of greenhouse gases you need to know?

A

Water vapour, carbon dioxide, nitrous oxide, methane and CFCs

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15
Q

What is the problem with the greenhouse effect?

A

Human beings are increasing the amount of greenhouse gases - this has enhanced the greenhouse effect
The result of this is that the Earth is heating up - global warming. This is a type of climate change that could lead to changing rainfall patterns and things like changing crop growth patterns or flooding due to melting polar ice caps.

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16
Q

What does each bar show on a pyramid of biomass?

A

The mass of the living material at that stage of the food chain.

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17
Q

What is a carnivore?

A

An organism that feeds on animals.

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18
Q

What are producers?

A

Plants which photosynthesis to produce food.

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19
Q

What are the two main ways that nitrogen fixation happens?

A

Lightning - there’s so much energy in a bolt of lightning that it’s enough to make nitrogen react with oxygen in the air to give nitrates
Nitrogen fixing bacteria - which can be found in some root nodules e.g. in leguminous plants or soil

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20
Q

Explain how the water cycle is disturbed as an effect of deforestation

A

Trees stop rainwater from reaching rivers too quickly
When they’re cut down, rainwater can run straight into rivers - this can lead to flooding
Transpiration from trees releases some of the rainwater back into the atmosphere
When they’re cut down this can make the local climate drier

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21
Q

What is the problem with nitrogen?

A

It is very unreactive so can’t be used directly by plants or animals

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22
Q

How does human activity contribute to global warming by releasing methane?

A

Cattle rearing (cattle’s flatulence) and fermentation by bacteria in rice paddy fields

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23
Q

Explain leaching as an effect of deforestation

A

Trees take up nutrients from the soil before they can be leached by rain, but return them to the soil when leaves die
When trees are removed nutrients get leaches away, but don’t get replaced, leaving infertile soil

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24
Q

What energy transfers occur in a food chain?

A
  1. Photosynthesis turns sunlight energy into chemicals such as glucose and starch.
  2. Respiration releases energy from glucose.
  3. Almost all other biological processes use the energy released in respiration.
  4. If the energy released in respiration is used to produce new cells then the energy remains fixed in molecules in the organism. It can then be passed onto the next trophic level of feeding.
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25
Q

What are CFCs?

A

Man-made chemicals that are really powerful greenhouse gases. They also damage the ozone layer, which protects us from UV radiation from the Sun

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26
Q

How does human activity contribute to global warming by releasing CO2?

A

CO2 is released in car emissions and industrial processes as we burn fossil fuels
Deforestation as burning trees releases CO2

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27
Q

What are the levels of a pyramid of numbers?

A

The lowest levels are the first stages of the food chain, usually the producers.

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28
Q

What is a community?

A

All the populations of living organisms living in an ecosystem at a particular time.

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29
Q

How does human activity contribute to global warming by releasing nitrous oxide?

A

Naturally released, but more is released from soils after fertiliser is used
Vehicle engines and industry

30
Q

What is another cause of eutrophication?

A

Pollution by sewage. Sewage also contains lots of phosphates from detergents, e.g. washing powder and nitrates from urine and faeces
These extra nutrients cause eutrophication in the same way that fertilisers do

31
Q

What is the problem with fertilisers?

A

Fertilisers can cause big problems when they end up in lakes or rivers
Nitrates and phosphates are put into fields as mineral fertilisers
If too much fertiliser is applied and it rains afterwards as these ions in the fertilisers are very soluble, nitrates are easily leached (washed through the soil) into rivers and lakes
The result is rapid eutrophication

32
Q

Where is most energy ‘lost’ from one trophic level to another?

A
  1. Energy released in respiration is used for other processes so it escapes as heat or carbon dioxide of water from the organism.
  2. Some parts of the food e.g. roots and bones aren’t eaten so the energy isn’t taken in.
  3. Some parts of the food are indigestible (e.g. fibre) so pass through the organism and come out on waste (e.g. faeces).
  4. 10% of the energy becomes biomass (is stored and used for growth).
33
Q

What is carbon?

A

Carbon is an important element and makes up all living things. But there is a fixed amount.

34
Q

What does each bar on the pyramid of numbers represent?

A

The numbers of the organism at that stage of the food chain.

35
Q

Describe the process of eutrophication

A

1) fertilisers enter the water, adding extra nutrients (nitrates and phosphates)
2) the algae in the water use the nitrates to make extra proteins for growth, forming an algae bloom, which blocks out sunlight
3) submerged plants can not photosynthesise due to a lack of sunlight and die
4) with more food available, microorganisms that feed on dead plants and algae (decaying them), increase in number and their respiration depletes all the oxygen in the water
5) therefore, organisms that need oxygen (e.g. fish) die

36
Q

How do plants get their nitrogen to make proteins?

A

From the soil. So nitrogen in the air has to be turned into nitrogen compounds (e.g. nitrates) before plants can use it.

37
Q

What are the effects of acid rain?

A

Acid rain can cause a lake to become more acidic - this has a severe effect on the lake’s ecosystem. Many organisms are sensitive to changes in the pH and can’t survive in more acidic conditions - many plants and animals die
Acid rain can also kill trees - the acid damages leaves and releases toxic substances from the soil, making it hard for the trees to take up nutrients
Acid rain also damages buildings

38
Q

What is a quadrat?

A

A square frame enclosing a known area.

39
Q

What is biomass?

A

The mass of the organic matter of an organism (‘dry’ mass)

40
Q

What shape are pyramids of biomass usually?

A

They are practically always pyramid shaped. This is because if you think about it, you can’t live off something that weighs less that you in organic matter.

41
Q

What are trophic levels?

A

Different feeding levels of a food chain/web.

42
Q

What is a habitat?

A

The place where specific organisms live.

43
Q

What is population?

A

All of the organisms of a particular species living in an ecosystem at a particular time.

44
Q

Why is the percentage energy transfer efficiently from sunlight to plants low?

A

Because the light misses the plant
Light misses the chloroplasts
Light is not absorbed
Light is reflected

45
Q

How do organisms interact with each other within an organism?

A

Organisms are constantly interacting with each other within an organism. Interactions include feeding relationships, competition between organisms, and relationships between the organisms and the physical environment.

46
Q

What is a herbivore?

A

An animal that feeds on vegetation.

47
Q

What is a Pyramid of numbers?

A

They represent the numbers of organisms in each trophic level of a food chain, irrespective of their mass.

48
Q

What is a pyramid of biomass?

A

It shows the total mass of the organism in each trophic level, irrespective of their numbers.

49
Q

Describe the carbon cycle

A

1) green plants use the carbon from CO2 in the air to make carbohydrates, fats and proteins by the process of phootsynthesis
2) eating passes the carbon compounds in the plant along to animals in a food chain or web
3) both plant and animal respiration releases CO2 back into the air
4) plants and animals eventually die and decompose, or are killed and turned into useful products (that contain carbon)
5) when plants and animals decompose they’re broken down by decomposers such as bacteria and fungi. This process returns carbon compounds to the soil, often forming fossil fuels. These decomposers also release CO2 by respiration as they break down material.
6) some useful plant and animal products e.g. wood and fossil fuels are burnt (combustion). This also releases CO2 back into the air

50
Q

What do pyramids of energy transfer show?

A

The energy transferred to each trophic level of a food chain.

51
Q

How does sulfur dioxide lead to acid rain?

A

When this gas combines with rain clouds it forms dilute sulfuric acid, which falls as acid rain

52
Q

What is the problem with carbon monoxide?

A

This is a poisonous gas. It combines quickly with haemoglobin in the blood. CO can kill people if the blood becomes so saturated with the gas that the blood can no longer carry enough oxygen for cellular respiration to take place.

53
Q

What are consumers?

A

Animals that eat other organisms.

54
Q

Why are there food webs and not just food chains?

A

There are many different species in an environment so there are lots of possible food chains. Often organisms do not feed on just one type of organism.

55
Q

How do you work out the distribution of organisms?

A
  1. Mark out a line (transect) in the area you want to study e.g. from the hedge in the middle of the field.
  2. Collect data along the line using quadrats placed next to each other.
56
Q

What would happen if there was a sudden decrease in the population of water spiders?

A
  1. There would be less food for frogs, so their numbers might decrease.
  2. The number of mayfly larvae may increase because the water spiders are not eating them.
  3. The diving beetles wouldn’t be competing with the water spiders for food, so their numbers might increase.
57
Q

What is an ecosystem?

A

A distinct, self-supporting system of organisms interacting with each other and with their environment.

58
Q

Why are pyramids of numbers often pyramid shaped? When are they not?

A

Every time you go up a trophic level, the number or organisms that will feed goes down. This is because it takes a lot of food from the level below to keep one animal alive. Sometimes it isn’t, e.g. 1 fox could feed 5000 flees.

59
Q

What is a food web?

A

Interconnecting food chains in an ecological community.

60
Q

Explain how the balance of oxygen is disturbed as an effect of deforestation

A

Fewer trees also means that less photosynthesis takes place, releasing less oxygen - this causes the oxygen level in the atmosphere to drop

61
Q

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

A

1) decomposers - they break down proteins (in rotting plants and animals) and urea (in animal waste) and turn them into ammonia (a nitrogen compound)
2) nitrifying bacteria - turns ammonia into nitrates
3) nitrogen fixing bacteria (+ lightning) - turns atmospheric nitrogen into nitrogen compounds plants can use
4) denitrifying bacteria - turns nitrates back into nitrogen gas (this has no benefit to us)

62
Q

Why do animals and plants need nitrogen?

A

To make proteins

63
Q

What does interdependent mean?

A

In a food web, all the species are interdependent meaning if one changes others are affected.

64
Q

Explain soil erosion as an effect of deforestation

A

Tree roots hold soil together

When trees are removed, soil can be washed away by the rain (eroded), leaving infertile ground

65
Q

How is sulfur dioxide released?

A

Burning fossil fuels releases SO2. The SO2 comes form sulfur impurities in the fuels. Mainly released from internal combustion engines in cars and from power stations

66
Q

Describe the water cycle

A

1) heat from the Sun makes water evaporate from the land and sea
2) plant transpiration and respiration of organisms also releases water vapour into the air
3) the warm water vapour is carried upwards (as warm air rises). When it gets higher up it cools and condenses to form clouds
4) water falls from the clouds as precipitation and is returned to the land and sea

67
Q

What is nitrogen fixation?

A

The process of turning nitrogen from the air into nitrogen compounds in the soil which plants can use

68
Q

How can carbon monoxide emissions be reduced?

A

Most modern cars are fitted with catalytic converters that turn the CO into CO2, decreasing the amount of CO that’s released into the atmosphere

69
Q

How much energy is transferred from one trophic level to the next?

A

About 10%

70
Q

What is environment?

A

The external conditions with which an organism interacts.

Biology GCSE (18 decks)

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