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AQA GCSE Biology > 7.2 Organisation of ecosystems (Triple) > Flashcards

7.2 Organisation of ecosystems (Triple) Flashcards

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1
Q

Define population

A

A species that occupy the same habitat

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2
Q

Define habitat

A

The place in which an organism lives

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3
Q

Define community

A

Populations of different species interacting

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4
Q

Define ecosystem

A

The interactions between the biotic and abiotic factors in an area

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5
Q

What do food chains show?

A

Food chains show the feeding relationships of different organisms and the flow of energy between the organisms

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6
Q

Define biomass

A

The total mass of living material

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7
Q

What are trophic levels?

A

The stages in a food chain

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8
Q

What do arrows in a food chain represent?

A

The direction of biomass transfer

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9
Q

Describe a simple food chain

A

● Producer

● Primary consumer

● Secondary consumer

● Tertiary consumer

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10
Q

What is a producer?

A

An organism that makes its own food

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11
Q

What types of organisms are producers?

A

Photosynthetic organisms like green plants and algae that trap energy from the Sun

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12
Q

What is a primary consumer?

A

An organism that feeds on producers

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13
Q

What is a secondary consumer?

A

An organism that feeds on primary consumers

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14
Q

What is a tertiary consumer?

A

An organism that feeds on secondary consumers

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15
Q

What is a predator?

A

A consumer that kills and eats other animals

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16
Q

What is prey?

A

An animal that is killed and eaten by another animal

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17
Q

Describe the pattern of predators and prey in a stable community

A

The numbers of predators and prey rise and fall in cycles

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18
Q

Why are producers the first trophic level?

A

● Producers provide all biomass for the food chain (production of glucose via photosynthesis)

● The rest of the food chain involves the transfer of the biomass

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19
Q

What piece of apparatus is used to measure the abundance and distribution of organisms in an area?

A

A quadrat

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20
Q

What piece of apparatus is used to study the distribution of organisms across a gradient?

A

Belt transect

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21
Q

When considering the abundance of organisms, what is meant by the term ‘mean’?

A

The average number of organisms

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22
Q

How is the arithmetic mean calculated?

A

Sum of each number of each organism / Total number of each type of organism

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23
Q

When considering the abundance of different organisms, what is meant by the term ‘mode’?

A

The most populous organism

24
Q

When considering the abundance of organisms, what is meant by the term ‘median’?

A

The organism that represents the middle value when the numbers of each organism are arranged from lowest to highest

25
Q

Describe how materials cycle through the living and non-living components of an ecosystem

A
  1. Organisms take in elements from the surroundings soil
  2. Elements converted to complex molecules which become biomass
  3. Elements transferred along food chains
  4. Elements return to the environment during excretion and decomposition of dead organisms
26
Q

Give three molecules which are cycled through ecosystems

A

● Oxygen
● Carbon dioxide
● Water

27
Q

Describe the carbon cycle

A
  1. Plants turn carbon dioxide into organic molecules during photosynthesis
  2. Organic carbon containing molecules are passed onto organisms that eat the plants
  3. Carbon dioxide is released back into the atmosphere by respiration from animals and plants

Burning fossil fuels also releases carbon dioxide into the atmosphere

28
Q

Why is the carbon cycle important?

A

Carbon containing molecules such as glucose are important for living organisms to grow and provide energy for vital functions within cells

29
Q

Describe the water cycle

A
  1. Water from lakes and oceans evaporates
  2. The evaporated water condenses into clouds and returns to earth as precipitation
  3. The water from precipitation is useful for life on land
  4. The water then returns to rivers and oceans through surface runoff
30
Q

Why is the water cycle important?

A

Living organisms require water and the water cycle provides organisms on land with a continuous supply of water

31
Q

Why are microorganisms important for the cycling of materials through an ecosystem?

A

Microorganisms (bacteria and fungi) return carbon to the environment by releasing carbon dioxide through respiration while they decompose dead matter.

The decomposition of dead matter in soil returns mineral ions to the environment for other organisms to use e.g. plants use mineral ions for growth

32
Q

What is meant by decomposition? (Triple)

A

The breakdown of dead materials into simpler organic matter

33
Q

How do decomposers break down dead matter? (Triple)

A

Decomposers release enzymes which catalyse the breakdown of dead material into smaller molecules

34
Q

What are the two types of decomposition? (Triple)

A

● Aerobic decomposition (with oxygen)

● Anaerobic decomposition (without oxygen)

35
Q

What factors affect the rate of decomposition? (Triple)

A

● Oxygen availability

● Temperature

● Water content

36
Q

Why is oxygen required for decomposition? (Triple)

A

Most decomposers require oxygen for aerobic respiration

37
Q

How does the availability of oxygen affect the rate of decomposition? (Triple)

A

● As oxygen levels
increase, the rate of decomposition increases

● As oxygen levels decrease, the rate of decomposition decreases

38
Q

Why can decomposition still occur in the absence of oxygen? (Triple)

A

Some decomposers respire anaerobically.

However, the rate of decomposition is slower as anaerobic respiration produces less energy.

39
Q

How does soil water content affect the rate of decomposition? (Triple)

A

Decomposers require water to survive:

● In moist conditions the rate of decomposition is high

● In waterlogged soil there is little oxygen for respiration so the rate of decomposition decreases

40
Q

Why does decomposition require water? (Triple)

A

Water is required for the secretion of enzymes and absorption of dissolved molecules

41
Q

How does temperature affect the rate of decomposition? (Triple)

A

Decomposers release enzymes:

● Rate highest at 50°C (optimum temperature for enzymes)

● Lower temperatures, enzymes work too slowly, rate decreases

-High
temperatures,
enzymes
denatured,
decomposition
stops

42
Q

How is the rate of change calculated when considering the decay of biological material? (Triple)

A

Rate of change = change in value / change in time

Where value is a measurable variable associated with the decay of the material

43
Q

What is compost? (Triple)

A

The nutrient-rich product of the rapid decay of waste biological material (dead plants and animal waste) in optimum conditions set by gardeners and farmers.

44
Q

How is compost used? (Triple)

A

Used as natural fertilizer to promote growth of crops or garden plants

45
Q

Describe how biogas generators work. (Triple)

A

Biogas generators provide methane gas for fuel to through anaerobic decomposition that occurs in animal waste

46
Q

Describe how environmental conditions affect communities. (Triple, Higher)

A

Environmental conditions (e.g. temperature, soil pH, light intensity) affect the abundance and distribution of organisms within communities

e.g. rising global temperatures have been linked to the extinction of frog species (their thin skin makes the more vulnerable to temperature changes).

47
Q

How can different temperatures be bad for certain communities.

A

If the temperature is too low, growth will be slower as organisms will use more energy to stay warm.

If the temperature is too high, organisms can die in water overcome limited as evaporation increases.

48
Q

How can changes in water levels affect ecosystems? (Higher)

A

Animals may have to migrate to find water

Melting ice caps may destroy the habitats of some animals (either animals living in icy regions or by sea level rise)

49
Q

How can atmospheric gases affect ecosystems? (Higher)

A

● Some organisms cannot survive when certain gases are present

● Polluted water can cause illness to animals that drink it

50
Q

What detrimental impacts can sulfur dioxide have on the environment?

A

Formed when fossil fuels containing impurities are burnt

Sulfur dioxide can dissolve in water to form acid rain which can erode buildings and pollute water sources

51
Q

What detrimental impacts can carbon monoxide have in the environment?

A

● Carbon monoxide is formed from the incomplete combustion of fossil fuels

● Carbon monoxide binds irreversibly to haemoglobin which prevents it from carrying oxygen

● Too much exposure can cause unconsciousness and death

52
Q

Name five greenhouse gases

A

● Water vapor
● Carbon dioxide
● Nitrous oxide
● Methane
● CFCs

53
Q

Give three human activities that contribute to greenhouse gases

A

● Burning fossil fuels

● Deforestation

● Large scale livestock farming

54
Q

How do greenhouse gases lead to global warming?

A

● Greenhouse gases allow heat from the Sun to enter the atmosphere

● The gases act as a ‘blanket’ and trap the heat in the atmosphere

55
Q

State three negative consequences of global warming

A

● Sea levels rise caused by melting ice icebergs

● Disrupted farming and agriculture

● Increased spread of diseases and warmer climates

AQA GCSE Biology (31 decks)

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