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Edexcel iGCSE Biology > Ecology and the Environment > Flashcards

Ecology and the Environment Flashcards

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1
Q

What is ecology?

A

The study of how organisms affect each other and are affected by other factors in the environment

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2
Q

What is an ecosystem?

A

The interaction of living (biotic) and non-living (abiotic) factors in a particular place e.g. rainforest

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3
Q

What is a habitat?

A

The place where a community of organisms live e.g. a pond or meadow

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4
Q

What is an environment?

A

The non-living (abiotic) factors in an area e.g. soil type, temperature

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5
Q

What is a species?

A

One type of organism that can reproduce to give fertile young e.g. bull frog

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6
Q

What is a population?

A

All of one species in a habitat e.g. number of bull frogs in a pond

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7
Q

What is a community?

A

All of the living organisms that live in one habitat e.g. the frogs, the carp and the kingfishers all living in the pond

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8
Q

What does biodiversity mean?

A

The variety of different species of organisms on Earth, or within an ecosystem

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9
Q

Why is a high biodiversity important?

A

It makes sure that ecosystems are stable, because different species depend on eachother for food and shelter

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10
Q

What are the different abiotic factors that affect communities?

A
  1. Environmental conditions e.g. light intensity, moisture level, soil pH
  2. Toxis chemicals e.g. chemical pesticides or fertilisers
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11
Q

What biotic factors can affect communities?

A
  1. Availability of food e.g. an increase in berries could lead to an increase in blackbirds
  2. Number of predators e.g. the number of lions decreases the number of gazelles
  3. Competition e.g. organisms competing with eachother for the same resources
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12
Q

What are the trophic levels in food chains?

A

Producers
Primary Consumers
Secondary Consumers
Tertiary Consumers

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13
Q

What does each bar show on a pyramid of numbers?

A

The number of organisms at that stage of the food chain

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14
Q

What does each bar show on a pyramid of biomass?

A

The mass of living material at that stage of the food chain
(how much all the organisms at each level would ‘weigh’ if you put them all together)

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15
Q

What does each bar show on a pyramid of energy transfer?

A

Show the energy transferred to each trophic level in a food chain (always in a pyramid shape)

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16
Q

Identify the process labeled A

A

Combustion -> The burning of fossil fuels

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17
Q

Identify the process labeled B

A

Respiration (by plants)

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18
Q

Identify the process labeled C

A

Photosynthesis

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19
Q

Identify the process labeled D

A

Decomposition

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20
Q

Identify the process labeled E

A

Respiration (by animals)

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21
Q

Identify the process labeled A

A

Nitrogen Fixation

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22
Q

Identify the process labeled B

A

Decomposition -> Carried out by bacteria and fungi

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23
Q

Identify the process labeled C

A

Nitrification

24
Q

Identify the process labeled D

A

Absorption of fertiliser/nitrates

25
Q

Identify the process labeled E

A

Denitrification

26
Q

Why is nitrogen needed for plants and animals?

A

To make amino acids, which make proteins. These are needed for growth

27
Q

What elements are found in proteins/amino acids?

A

CHON
(Carbon, Hydrogen, Oxygen, Nitrogen)

28
Q

What is nitrogen fixation?

A

The process of turning nitrogen (gas from the air) into nitrogen compounds (like nitrates/nitrites)

29
Q

What are the two ways nitrogen fixing happens?

A

Lighting -> The energy from a bolt of lightning makes nitrogen react with oxygen to form nitrates

Nitrogen-fixing bacteria

30
Q

What are the four bacteria involved in the nitrogen cycle?

A

Decomposers

Nitrifying bacteria

Nitrogen-fixing bacteria

Denitrifying bacteria

31
Q

What do decomposers do in the nitrogen cycle?

A

They break down proteins (in rotting plants/animals) and urea (in animal waste)

They then turn it into ammonia which then forms ammonium ions in the soil

32
Q

What do nitrifying bacteria do in the nitrogen cycle?

A

Turn ammonium ions into nitrites (NO2 -), and then nitrates (NO3 -)

33
Q

What do nitrogen-fixing bacteria do in the nitrogen cycle?

A

Turn atmospheric nitrogen gas into nitrogen compounds that plants can use

34
Q

What do denitrifying bacteria do in the nitrogen cycle?

A

Turn nitrates back into nitrogen gas (don’t like it)

35
Q

In what type of soil do de-nitrifying bacteria thrive?

A

Waterlogged

36
Q

Where can nitrogen-fixing bacteria be found?

A

Free-living in the soil

Root nodules of leguminous plants (e.g. beans, clover, peas etc)

37
Q

Why should farmers avoid growing the same crop in a field every year?

A

Because that crop would use up the same minerals and ions, and they would never be replenished

38
Q

How would a crop rotation system using clover increase crop yields?

A

Clover is a leguminous plant with nitrogen-fixing bacteria in its root nodules

The nitrogen-fixing bacteria will release nitrates into the soil

The nitrates can then be used to make plant proteins which leads to more plant growth

39
Q

Why is Carbon Monoxide (CO) poisonous?

A

It combines with haemoglobin in red blood cells, which prevents them from carrying oxygen

40
Q

How is acid rain created?

A

Sulfur dioxide comes from impurities in the fossil fuels

When this gas is mixed with rain clouds, it forms dilute sulfuric acid

This then falls as acid rain

41
Q

What are the main causes of acid rain?

A

Internal combustion engines in cars
Power stations

42
Q

Why is acid rain bad for the environment?

A

Can cause lakes to become acidic which causes many organisms to die

Can kill trees. The acid damages leaves and releases toxic substances from the soil

43
Q

What environmental issues are caused by climate change?

A

Extreme weather

Rising sea levels and flooding -> melting ice caps

44
Q

How is carbon dioxide released into the atmosphere?

A

Combustion (burning fossil fuels)

Deforestation (less trees to take CO2 in from the atmosphere)

45
Q

How is methane released into the atmosphere?

A

Produced naturally (e.g. from rotting plants)

Rice-growing

Cattle rearing

46
Q

How is methane released into the atmosphere?

A

Produced naturally (e.g. from rotting plants)

Rice-growing

Cattle rearing

47
Q

How is nitrous oxide released into the atmosphere?

A

Released naturally by bacteria in soils and the ocean

A lot is released from soil after fertiliser is used

48
Q

How does eutrophication happen?

A

Fertilisers enter the water, adding extra nutrients

The extra nutrients cause algae to grow fast and block out the light

Plants can’t photosynthesise due to lack of light and start to die

With more food available (dead plants), microorganisms increase in number and deplete all the oxygen in the water

Organisms that need oxygen die

49
Q

How does deforestation affect the environment?

A

Leaching

Soil erosion

Disturbing evapotranspiration

Disturbing the balance of carbon dioxide and oxygen

50
Q

What is leaching?

A

Rain washing away (leaching) nutrients from the soil

51
Q

How do trees stop leaching?

A

Trees take up nutrients from the soil before they can be leached, but returns them to the soul when leaves die

52
Q

Why does leaching increase after deforestation?

A

When trees are removed, nutrients get leached away but don’t get replaced, leaving infertile soil

53
Q

How do trees prevent soil erosion and what happens when they are cut down?

A

Tree roots hold the soil together

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

54
Q

How do trees maintain the balance of carbon dioxide and oxygen?

A

Forests take up CO2 by photosynthesis and store it in wood

Trees slowly release CO2 as they decompose

55
Q

What happens to the balance of CO2 and O2 when trees are cut down?

A

Fewer trees means less photosynthesis which leads to more CO2 and less O2 in the atmosphere

When trees are burned, they release CO2. This disturbs the carbon cycle and contributes to global warming

56
Q

What is evapotranspiration?

A

Both the processes of water avaporating from the Earth’s surface and plant transpiration.

This water falls back to the Earth as rain

57
Q

How does deforestation disturb evapotranspiration?

A

When trees are cut down, ev

Edexcel iGCSE Biology (10 decks)

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