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iGCSE Biology > Cycles within ecosystems > Flashcards

Cycles within ecosystems Flashcards

1
Q

What organism is involved in decomposition?

A

decomposers

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1
Q

What organism is involved in nitrogen fixation?

A

nitrogen fixing bacteria

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2
Q

What organism is involved in nitrification?

A

nitrifying bacteria

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3
Q

What organism is involved in denitrification?

A

denitrifying bacteria

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4
Q

Describe the process of decomposition

A

conversion of waste products into ammonia

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5
Q

Describe the process of nitrogen fixation

A

conversion of nitrogen gas into ammonia

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6
Q

Describe the process of nitrification

A

oxidation of ammonia into nitrites then nitrates

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7
Q

Describe the process of denitrification

A

nitrates are used as energy
nitrogen gas released

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8
Q

Explain why farmers would grow pea plants and then plough the roots through their fields

A

pea plants are leguminous so have root nodules which contain nitrogen fixing bacteria
bacteria decompose
increase soil fertility due to ammonia that can -> nitrates

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9
Q

Which compounds in living things contain nitrogen?

A

protein and nucleic acid

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10
Q

Which compounds in living things contain carbon?

A

carbohydrates, lipids, protein and nucleic acid

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11
Q

Describe the process of saprotrophic feeding

A

bacteria and fungi release enzymes to break down an organism or waste products

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12
Q

What is a community?

A

all populations of different species living together in a particular place at a particular time

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13
Q

What are abiotic factors?

A

non-living parts of an ecosystem

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14
Q

What are biotic factors

A

living components of an ecosystem

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15
Q

What is biodiversity?

A

variety of living organisms in an ecosystem

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16
Q

What is distribution?

A

spread of living organisms

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17
Q

What is an ecosystem?

A

community of organisms and non living components of a particular area and how they interact with one another

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18
Q

What is a habitat?

A

place in an ecosystem when an organism lives

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19
Q

What is population?

A

all the organisms of the same species living with one another in a habitat at any one time

20
Q

What are decomposers?

A

organisms that release enzymes which speed up breakdown of dead material

21
Q

What are energy transfers?

A

the flow of energy from one trophic level to the next

22
Q

What does a food chain show?

A

feeding relationships between organims

23
Q

What is a food web?

A

network of food chains

24
Q

What is a primary consumer?

A

herbivores
consume producers

25
Q

What are producers?

A

photosynthetic organisms that provide biomass for all organisms in food chain

26
Q

What is a pyramid of biomass?

A

pyramid with each layer representing amount of mass of living material at each trophic level of food chain

27
Q

What is a pyramid of number?

A

pyramid showing numbers of each organism at each trophic level

28
Q

What is a quadrat?

A

square grid

29
Q

What are quaternary consumers?

A

carnivores
consume tertiary consumers

30
Q

What are secondary consumers?

A

carnivores
consume primary consumers

31
Q

What are tertiary consumers?

A

carnivores
consume secondary consumers

32
Q

What is an apex predator?

A

organism not consumed by another

33
Q

What is a trophic level?

A

position of an organism in a food chain

34
Q

Why is it better to draw a pyramid of biomass rather than a pyramid of numbers?

A

pyramid of numbers are variable, pyramid of biomass always look the same

35
Q

Describe how we can use a quadrat to measure population

A

estimate % cover of species OR count number of particular species

36
Q

Describe how we can use a quadrat to measure diversity

A

count number of different species

37
Q

Give examples of abiotic factors

A

temperature, light intensity, moisture, soil pH, CO2 and O2 levels

38
Q

Give examples of biotic factors

A

food availability, pathogens, predation and competition

39
Q

What organisms are decomposers?

A

bacteria and fungi

40
Q

What happens to the amount of energy transferred as you move up the food levels?

41
Q

Why does the amount of energy transferred decrease as you move up the food levels?

A

energy used respiration/movement
lost in excretory products

42
Q

What do the arrows represent in a food chain?

A

flow of energy

43
Q

Why are food webs better than food chains?

A

more realistic
animals feed on one or more organism

44
Q

What is a quadrat used for?

A

sample populations abundance
distribution
of organisms

45
Q

How much energy is transferred between trophic levels?

A

only 10% transferred from one to the next

46
Q

Where are nitrogen fixing bacteria found?

A

root nodules of legumes
soil

47
Q

Give examples of decomposers

A

fungi
bacteria

iGCSE Biology (22 decks)

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