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Biology edexcel 9-1 > Topic 9 > Flashcards

Topic 9 Flashcards

1
Q

Describe individual?

A

A single organism

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2
Q

Describe Population?

A

All the organisms of one species in a habitat

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3
Q

Describe community?

A

All the organisms of different species living in a habitat

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4
Q

Describe ecosystem

A

A community of organisms along with all the non-living (abiotic) conditions

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5
Q

What abiotic factors affect communities?

A
  1. Temperature
  2. Amount of water
  3. Light intensity
  4. Pollutants
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6
Q

What biotic factors affect communities?

A
  1. Competition

2. Predation

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7
Q

Describe the importance of interdependence in a community?

A

organisms depend on each other for things like food and shelter in order to survive and reproduce so a change in the population of one species could have a knock on effect for other species in the same community

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8
Q

What is mutualism?

A

Mutualism is a relationship between 2 organisms in which both organisms benefit.

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9
Q

What is parasitism?

A

Parasites live very closely with a host species and benefits from them by taking what it needs. The host doesnt benefit.

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10
Q

What is a trophic level?

A

A trophic level is each stage of a food chain

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11
Q

What happens to energy as you go up a biomass pyramid and how does this affect the shape of the pyramid?

A

Each time you go up a trophic level, the mass of the organisms decreases as energy is lost and so does not become biomass in the next level. This gives a rise to the pyramid shape

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12
Q

How do you work out the efficiency of energy transfer?

A

Efficiency = (energy transferred to next level/ energy available at previous level) *100

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13
Q

What is biodiversity?

A

Biodiversity is the variety of living organisms in an ecosystem

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14
Q

How does fish farming reduce biodiversity?

A
  1. Food is added to the nets to feed fish. This can cause waste and therefore eutrophication. This can then cause the death of wild species
  2. It can act as a breeding ground for parasites. The parasites can leave the farm and infect wild animals, sometimes killing them
  3. Predators may be attracted to the nets, be trapped in them and die
  4. Farmed fish that escape into the wild can cause problems for indigenous species
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15
Q

How can fish farming be low in biodiversity?

A

Fish can be farmed in large tanks. These farms are low in biodiversity as they only farm for one species. The tanks are kept free of plants and predators, and any parasites or microorganisms are usually killed

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16
Q

How can the introduction of non-indigenous species reduce biodiversity?

A
  1. The non-indigenous species may be better at finding resources to survive than the indigenous species. They may out-compete the indigenous species, who eventually die out
  2. They sometimes bring new diseases to a habitat which can kill off the indigenous species
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17
Q

How can fertilisers cause eutrophication?

A
  1. Fertilisers enter the water, adding excess nitrates
  2. The excess nitrate cause algae to grow fast and blocks out light
  3. Plants cant photosynthesise due to lack of light and start to die and decompose
  4. Micro-organisms that feed on decomposing plants increase and uses up the oxygen
  5. Organisms that need the oxygen for aerobic respiration die
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18
Q

How can reforestation increase biodiversity?

A

Growing lots of different types of trees in an area can provide food and shelter for lots of different animal species

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19
Q

describe some conservation methods that can help protect at-risk species?

A

1- Protecting a species natural habitat
2- Protecting species in safe areas outside of their natural habitat and introducing captive breeding programmes to increase numbers
3- The use of seed banks to store and distribute the seeds of rare and endangered plants

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20
Q

What are the benefits of maintaining biodiversity?

A 
1- protecting the human food supply
2- ensuring minimal damage to food chains (protect a species)
3- providing future medicines 
4- Cultural aspects 
5- Ecotourism
6- providing new jobs
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21
Q

How does an increase in the population affect food security?

A

Global food production has to increase so everyone has enough food that will have the right balance of nutrition

22
Q

How can increased animal farming and the consumption of meat and fish affect food security?

A

1- over fishing could mean there will not be enough fish in the future
2- There’s less energy and less biomass everytime you move up a trophic level so for a given area of land, you can produce a lot more food for humans by growing crops than by grazing animals
(animals and fish being reared are often fed crops that would otherwise be eaten by humans)

23
Q

How can environmental changes caused by human activity affect food security?

A
  • Carbon dioxide, rising temperature, global warming, can affect crop growth, and so reduce yields.
24
Q

How can new pests and pathogens affect food security?

A

They can damage crops and livestock e.g they can infect crops with diseases that the crops are not resistant against. This reduces crop yield

25
Q

What is sustainability and how does it affect food security?

A

Sustainability means meeting the needs of todays population without affecting the needs of future populations.
- e.g using biofuels instead of crops may make it too expensive for farmers in some areas to continue farming and producing food in the future

26
Q

How do different materials cycle through the abiotic and biotic components of ecosystems?

A

1- Living things are made of elements they take from the environment e.g. plants take in C/ O from air and N from the soil
2- They turn these elements into complex compounds (carbohydrates, proteins and fats) that make up living organisms. Elements are passed along food chains when animals eat the plants and each other
3- waste products and dead organisms are broken down by decomposers and the elements in them are put back in the soil or air, and the cycle starts over

27
Q

Describe the carbon cycle

A

1) one arrow downwards from CO2 in air (Photosynthesis to make complex compounds)
2) eating passed the compounds into food chain
3) Both animal and plant respiration releases CO2 back in air
4) Dead organisms are broken down by decomposers which releases CO2 back into air
5) Some useful plant and animal products are burned e.g. wood and fossil fuels, releasing CO2 into air.
6) decomposition of materials means that habitats can be maintained for the organisms that live there e.g nutrients returned to soil

28
Q

Describe the water cycle

A
  1. Evaporation
  2. Transpiration
  3. condensation
  4. precipation
29
Q

When do droughts occur?

A

Droughts occur when there isnt enough precipitation falling from the sky

30
Q

What is desalination?

A

Desalination is a method that removes salts (mineral ions) from salt water to make water pure. e.g. thermal desalination

31
Q

How can reverse osmosis be a method of desalination?

A

1- Salt water is treated to remove solids, before being fed at a high pressure into a vessel containing a partially permeable membrane

  1. pressure causes water molecules to move in opposite direction - from high salt conc to a low salt conc
  2. as water is forced through membrane , salts are left behind.
32
Q

What are indicator species?

A

These are species that are very sensitive to change and so therefore can be used to study the effect of human activities

33
Q

What can cause water pollution?

A

eutrophication

34
Q

What do the presence of freshwater shrimps and stonefly larvae indicate?

A

Clean water

35
Q

What do the presence of blood worms and sludgeworms indicate?

A

Dirty water

36
Q

What does bushy and crusty lichen indicate?

A

Clean air (bushy lichen will most commonly appear in clean air)

37
Q

What does blackspot fungus on roses indicate?

A

a presence of clean air

38
Q

How can temperate affect the rate of decay?

A

A warm (not too high) temperature increases the rate of enzyme-controlled reactions

39
Q

How can water content affect the rate of decay?

A

Decay is faster in moist environments as the organisms involved in decay need water to survive and carry out biological processes

40
Q

How can oxygen availability affect the rate of decay?

A

The rate of decomposition is faster as organisms need oxygen for aerobic respiration. (some dont need oxygen to respire, but these micro-organisms work slower anyway)

41
Q

How can temperature help preserve food?

A

Keeping food in the fridge slows down the rate of decomposition

42
Q

How can releasing water content help preserve food?

A

This removes the water that microorganisms need to survive and reproduce, and so therefore they will not be able to decompose

43
Q

How can storing food in airtight cans preserve food?

A

It stops micro-organisms from getting in and decomposing the food. The cans are sealed and sterilised after the food is in so that they are killed

44
Q

Describe the nitrogen cycle?

A
  1. Nitrogen is turned into mineral ions,
  2. Plants use these ions to make proteins
  3. Animals eat the nitrogen in the form of protein
  4. Decomposers break down the proteins found in dead animals and urea waste and therefore nitrogen is released back into the atmosphere
45
Q

What is nitrogen fixation?

A

This is the process of turning N2 from the air into nitrogen containing ions in the soil that plants can use

46
Q

Give two ways that nitrogen fixation can happen?

A

1) Lightning - theres so much energy in lightning that its enough to make the nitrogen react with oxygen in the air to give nitrates
2) Nitrogen-fixing bactera in roots and soils

47
Q

what are the 4 different types of bacteria that are involved in the nitrogen cycle?

A

1) decomposers - they decompose proteins and urea and turn them into ammonia. These can form ammonium ions that plants can use
2) Nitrifying bacteria - Turning ammonia in decaying matter into nitrites and then into nitrates
3) Nitrogen-fixing bacteria - Turn atmospheric N2, into ammonia, which forms ammonium ions
4) Denitrifying - Turns nitrates back into N2 gas this is of no benefit to organisms and they are often found in waterlogged soils

48
Q

Where do nitrogen-fixing bacteria live?

A

Some live in soil whilst others live in nodules on the roots of legume plants. When these plants decompose, the nitrogen stored in nodules is returned to the soil. Nitrogen ions can also leak out of the nodules during growth

49
Q

What is the mutualistic relationship between the plants and the bacteria?

A

The bacteria get food, and the plant gets nitrogen ions from the bacteria to make proteins

50
Q

What is crop rotation?

A

Crop rotation is growing different crops each year in a cycle. The cycle usually includes a nitrogen-fixing crop, which helps put nitrates back into the soil for another crop to use the following year

51
Q

What can fertilisers do for the nitrogen cycle?

A

Spreading manure and compost on fields recycle the nutrients left in plants and animal waste and returns them to the soil through decomposition. Artificial fertilisers that contain nitrates can be used, but these can be expensive

52
Q

What can cause poor crop growth and deficiency diseases?

A

This happens when the nitrogen content in the soil decreases

Biology edexcel 9-1 (8 decks)

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