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Biology Paper 2 > B17 Organising an ecosystem > Flashcards

B17 Organising an ecosystem Flashcards

1
Q

Write the word equation for photosynthesis

A

carbon dioxide + water -> glucose + oxygen

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2
Q

What is a community?

A

A group of interdependent organisms living in an ecosystem

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3
Q

Give examples of adaptations of animals that live in the desert

A

Produce concentrated urine, large SA to volume ratio, large ears, stay in burrows when temperature is highest

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4
Q

Give examples of adaptations of plants that live in the desert

A

Small surface area to volume ratio, fewer stomata, spines to prevent being consumer by herbivores, deep roots

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5
Q

What are the factors that affect the decay process?

A
  • temperature levels
  • oxygen levels
  • moisture levels
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6
Q

What is a trophic level?

A

The position of organisms within a food chain

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7
Q

Diagram of a food chain

A

producer, primary consumer, secondary consumer, tertiary consumer

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8
Q

Describe the predator and prey cycle

A
  • If there is plenty of food available, the number of prey increases as they can reproduce successfully
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9
Q

What is biomass?

A

The mass of material in living organisms (often measured as the dry mass of biological material in grams)

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10
Q

What is the problem with measuring dry biomass?

A
  • Could kill the organism
  • It is a very slow process
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11
Q

Why might a measure of wet biomass be less useful?

A
  • Wet biomass can vary based on environmental conditions, water levels between organisms can be very different
  • Water enters and leaves an organism freely and is not transferred between organisms, cannot track how water/energy is transferred up the food chain
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12
Q

No matter how long the food chain, what is the original source of the biomass?

A

The sun

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13
Q

Why is a measure of biomass more useful than a measure of the number of organisms?

A

The number of organisms does not accurately reflect what is happening to biomass, the size of the organism matters as well

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14
Q

What can be said about pyramids of biomass and give reasons why?

A
  • The amount of biomass at each trophic level of a food chain is always less than it was at the previous level
  • Not all organisms or parts of organisms are eaten by the stage above
  • Some of the biomass taken in is passed out and lost as waste
  • Large amounts of biomass take in at each trophic level are used in respiration to transfer energy to the organism and only a small proportion is used to build new biomass in the organism
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15
Q

How to calculate the efficiency of biomass transfer

A

biomass available after the transfer / biomass available before the transfer x 100

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16
Q

Which process in plants requires water?

A

Photosynthesis

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17
Q

Which process in living organisms produces water?

A

Respiration

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18
Q

Which process is the loss of water vapour from the leaves of the plant through the stomata, involving the evaporation of water from surface cells?

A

Transpiration

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19
Q

What is precipitation?

A

Anything that falls from the sky e.g. rain, snow, hail

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20
Q

How does carbon present in carbon dioxide in the air end up as part of a starch molecule in plants?

A
  • Diffuses through stomata
  • Photosynthesis
  • Translocation of sugars
  • Converted to starch for storage
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21
Q

Why would a farmer spread manure on crop fields?

A

To increase availability of mineral ions such as nitrates and magnesium

22
Q

What are decomposers?

A

Microorganisms that break down the waste and the dead animals and plants

23
Q

Describe the carbon cycle

A
  • Carbon dioxide is removed from the air in photosynthesis by green plants and algae, they use the carbon to make carbohydrates, proteins and fats, the carbon is passed on through food chains
  • Carbon dioxide is returned to the air when plants, algae and animals respire, when they die their bodies are broken down by decomposers, carbon is released into the atmosphere as carbon dioxide as decomposers respire
  • Carbon dioxide is returned to the air when wood or fossil fuels are burnt as they contain lots of carbon from photosynthesis
24
Q

Describe the water cycle

A
  • Evaporation: the Sun heats up the Earth’s surface and water is turned from a liquid into water vapour, forming warm moist air
  • Transpiration and respiration: loss of water vapour from plants and animals directly into the atmosphere
  • Condensation: as moist air rises it cools, water vapour condenses back into liquid water droplets producing clouds
  • Precipitation: as water droplets in clouds get heavier they fall as rain, snow or hail and this runs into lakes
  • Percolation: water trickles through gaps in soils and rocks, also runs into seas and the cycle begins again
25
Q

What factors affect the rate of decay?

A
  • Oxygen levels
  • Moisture levels
  • Temperature
26
Q

How does oxygen levels affect the rate of decay?

A
  • Most decomposers respire aerobically
  • So they need oxygen to break down food, transfer energy, grow and reproduce
  • Decay takes place more rapidly in aerobic conditions when there is plenty oxygen available
27
Q

How does moisture levels affect the rate of decay?

A
  • Most microorganisms grow faster in moist conditions
  • The moisture makes it easier for them to digest their food and also prevents them from dying out
  • Decay takes place far more rapidly in warm, moist conditions than it does in cold, dry ones
28
Q

How does temperature affect the rate of decay?

A
  • Chemical reactions in micro-organisms work faster in warm conditions
  • They slow down and might even stop if conditions are too cold
  • Decay also stops if it gets too hot, the enzymes in decomposers are denatured
29
Q

Describe the differences and similarities between making compost aerobically and anaerobically

A
  • If the microorganisms have oxygen, they respire aerobically and transfer energy to their surroundings, killing off weed seeds and speeding up the process, releases methane (biogas)
  • Without oxygen the process does not cause a rise in temperature and is slower
  • The warmer the compost mixture, the faster the compost mixture will be made, the decay process is also faster in moist conditions
30
Q

Describe why the processes of decay are so important in keeping the soil fertile

A
  • Plants remove minerals from the soil constantly, when animals eat plants these minerals are passed on through food chains and webs
  • If minerals were never returned to soil, soil would soon be infertile
  • Decay enables minerals that have become part of bodies of living organisms to be recycled and returned to environment
31
Q

Name the two types of organisms involved in the processes of decay

A
  • Detritivores
  • Decomposers
32
Q

Explain the difference between predators and prey animals

A

Predators are carnivores - they hunt and eat herbivores or other carnivores
Prey are usually herbivores - they are hunted and eaten by larger predators

33
Q

How does freezing food stop decomposition from taking place?

A

Low temperature prevents the growth of microorganisms

34
Q

How does cooking food stop decomposition from taking place?

A

High temperature denatures enzymes in microorganisms

35
Q

What can methane be used as?

A
  • Fuel for heating, cooking and generating electricity
  • Fuel for vehicles
36
Q

Garden and kitchen waste added to a compost bin rot down and become compost much more rapidly in the summer than in the winter. Explain why.

A
  • Rate of chemical reactions in microorganisms acting as decomposers speeds up with an increase in temperature
  • Average temperatures in summer a much warmer in summer than winter, so rate of decomposition increases
37
Q

During a particularly hot, dry summer, compost formation may slow down. Suggest a possible explanation for this.

A
  • Moisture makes it easier for microorganisms to digest their food and prevents them from drying out
  • Therefore they grow better in most conditions
  • The rate of decomposition decreases in dry conditions, even if the temperature is high
38
Q

Turning over the contents of a compost bin every so often can increase the rate at which decomposition takes places. Explain why.

A
  • Many microorganisms involved in decomposition need oxygen for aerobic respiration
  • Turning over a compost bin contents increases the air in the mixture
  • Increases rate of decomposition as microorganisms have plenty of oxygen for aerobic respiration
39
Q

What is the carbon cycle?

A

Cycling of carbon between living organisms and the environment

40
Q

Name the three main processes involved in the carbon cycle

A
  • Photosynthesis
  • Respiration
  • Combustion
41
Q

Explain why the carbon cycle is important for life on Earth

A
  • Prevents the Earth’s fixed amount of carbon dioxide from depleting
  • Returns carbon dioxide to the atmosphere for photosynthesis
42
Q

Name three sources of carbon dioxide for photosynthesis in plants

A
  • In the air
  • Dissolved in water
  • Produced as plants respire
43
Q

Explain why decomposers are so important in a stable ecosystem

A
  • Decomposers break down plant and animal waste and dead animals and plants
  • Returning resources removed from the environment by plants to the environment
  • The constant recycling of materials often leads to very stable ecosystems
44
Q

Materials in an ecosystem are described as being recycled. Explain what this means.

A
  • Living organisms remove materials from the environment constantly
  • If mineral ions taken from the soil by plants were not replaced, Earth’s resources would be depleted quickly
  • Decomposers break down plant and animals waste and dead animals and plants return mineral ions to the soil to be taken up by plants again
  • And carbon to the atmosphere as carbon dioxide to be used by producers in photosynthesis
45
Q

Plan an investigation to estimate the size of a population of ragwort growing in a rectangular field on a farm

A
  • Using a quadrat of a given area e.g. 0.25 m squared
  • Quadrats are placed randomly by obtaining random coordinates using a calculator
  • Suitable number of quadrats (10 or more)
  • Count the number of plants in each quadrat
  • Calculate mean per quadrat
  • Determine the area of the field
  • Population = mean per m squared x area of field
46
Q

Suggest three ways the scientists could maintain a high rate of reproduction in the bacterial culture

A
  • Increase the temperature
  • Add more oxygen
  • Add more amino acids
47
Q

Explain the advantage of making crop plants resistant to glyphosate

A
  • Can use glyphosate to kill weeds as it won’t affect the crop
  • So less competition for nutrients e.g. light, water
  • So crops have a higher yield
48
Q

Explain why the fermenter is sterilised before use

A
  • Kills microorganisms
  • Which compete for food and oxygen
49
Q

Explain why Fusarium needs glucose and oxygen

A
  • For aerobic respiration
  • which releases energy for growth
50
Q

Suggest why it is useful for bubbles of air and materials to move around inside the fermenter

A
  • So Fusarium can grow faster
  • And get sufficient food, glucose and minerals
51
Q

Why is it more efficient for humans to get energy by eating cereals than by eating chickens?

A
  • Chickens use energy for movement to keep warm
  • Much of the food eaten by chickens is wasted as faeces

Biology Paper 2 (10 decks)

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