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Biology > CB9- Ecosystems And Material Cycles > Flashcards

CB9- Ecosystems And Material Cycles Flashcards

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1
Q

what are the levels of ecosystem organisation?

A
  • ecosystems
  • community
  • population
  • individual
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2
Q

what is an ecosystem?

A

a community of organisms along with all the biotic and abiotic factors.

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3
Q

what is a community?

A

all the organisms of different species living together in a habitat.

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4
Q

what is a population?

A

all the organisms of one species living in the same habitat

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5
Q

what is an individual?

A

a single organism.

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6
Q

what is interdependence in a community?

A
  • communities will be made up of many populations that are interdependent on one another for resources like food and shelter in order to reproduce
  • this means that a change in one particular population would have effects on other species in the community eg. if a specie were to decrease in numbers this would disrupt the food chain.
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7
Q

what is mutualism?

A
  • relationship between 2 organisms where both benefit
  • eg. bees and flowers, bees receive pollen which they can spread to other plants for reproduction
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8
Q

what are parasites?

A
  • when only one organism (the parasite) benefits by feeding off the host organism, causing harm to the host
  • it lives on or in the host
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9
Q

what does abiotic mean?

A

non living

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10
Q

what does biotic mean?

A

living

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11
Q

what are some abiotic factors?

A
  • temperature
  • amount of water
  • light intensity
  • levels of pollutant
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12
Q

how does temperature cause changes to the community?

A
  • rises in average temperatures or severe drops can cause communities change, for example the distribution of species may change as they migrate or decrease in population
  • an absence of a specie that was once apart of a community is disruptive as it affects the food chain and also the interdependence
  • rising temps can increase the rate of photosynthesis creating an increase to plant growth
  • animals will be warmer meaning they can spend less of their energy for warmth and more for growth
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13
Q

what is distribution?

A

where organism are found in an ecosystem.

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14
Q

how does the amount of water cause changes to the community?

A
  • water access for animals for life
  • soil must be in good condition (slightly damp) for plants to grow best
  • if soil is waterlogged or too dry plant populations can decrease
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15
Q

how does light intensity cause changes to the community?

A
  • helpful in photosynthesis, helps plants grow
  • if more trees were to grow more shade can be provided causing grass to become dry as it cannot adapt to the lack of light, grass can be replaced with fungi or moss which are adapted to cope with low light intensity
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16
Q

how do levels of pollutant cause changes to the community?

A
  • human activity releases pollutants which can poison organisms
  • plastic could be eaten by organisms
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17
Q

what are some biotic factors?

A
  • plants
  • animals
  • dead animals
  • predation- living process
  • competition- living process
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18
Q

what is competition?

A
  • organisms compete with other species (and their own) for the same resources
  • this is biotic because living things are affecting one another
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19
Q

what is predation?

A
  • predators control populations because if a number of predators were to decrease, pray would increase causing overpopulation
  • the prey of the prey will also have more predators causing their populations to decrease
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20
Q

how can quadrants be used to study the distribution of organisms in different sample spaces?

A
  1. place a quadrant on the ground at a random point within the first sample area
  2. count all the organisms within the quadratic
  3. repeat
  4. then work out the mean number of organisms within the first sample (total number of organisms/number of quadrats)
  5. repeat the same process in the other sample areas and compare the different means
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21
Q

when using quadrants to study separate sample spaces how do you pick the points you place the quadrant in?

A
  • this random point can be found by dividing the sample area into a grid and using a random number generator to pick co ordinates
  • this is allows the results to be unbiased
22
Q

how do you estimate the total population size of an organism in a field using data from a random sample?

A

times the mean by the total area

23
Q

what is a gradient?

A
  • abiotic factors can create changes across habitats, this is known as a gradient
  • quadrants can show how organisms change along the gradient and how they are distributed eg. shaded areas will have less plant growth than a sunny area
24
Q

how do you measure the changes along a gradient using a belt transect?

A
  • a belt transient is a line of quadrats
    1. mark out a line in the area you want to study eg. shaded tree to the middle of a field
    2. collect data along this line by using quadrats placed next to eachother, if the transect is really long you can place the quadrants at regular intervals instead
    3. count organisms within the quadrat
    4. this allows you to find the mean number of organisms for each quadrat showing whether abiotic factors is correlated with a change in the distribution of species
25
Q

what is eutrophication?

A

an excess of nutrients is added to a habitat than it usually has.

26
Q

what is biodiversity?

A

the variety of living organisms in an ecosystem.

27
Q

how does eutrophication occur?

A
  1. fertiliser is added to fields, these are usually nitrates and phosphates
  2. if too much fertiliser is added and it rains afterwards, nitrates and phosphates will dissolve in the soil, but the nitrates and phosphates that are not taken up by plants are washed into streams, rivers and lakes
  3. this causes there to be excess nutrients in the water, high nitrate and phosphate concentrations in the water encourage plants and algae to grow rapidly
  4. this creates surface plants that will block sunlight causing plants in the water to have no access to light, therefore not be able to do photosynthesis and eventually die. these dead plants also won’t be able to produce oxygen
  5. the bacteria that breaks down dead materials increases in numbers (since they have more food available with the plants being dead) and it will use up more oxygen from the water.
  6. this makes the overall concentration of oxygen decrease so aquatic organisms would die
28
Q

what are 3 ways that humans have negative effects on biodiversity?

A
  • eutrophication
  • fish farming
  • introducing non indigenous species
29
Q

how does fish farming reduce biodiversity?

A
  • uneaten food and faeces from the fish can produce huge amounts of waste that could leak into open water, possibly causing eutrophication and the death of wild organisms
  • fish farms in open water are more susceptible to the rapid spread and breeding of parasites, because fish are more confined
  • predators could be attracted to the pens and try to get in but get stuck in the nets and die
  • farmed fish could escape into the wild which can take diseases to wild indigenous populations
  • fishes farmed in tanks have low biodiversity because only one type of species is farmed in the artificial tanks and no other organisms like plants
30
Q

what is fish farming?

A

aims to produce more fish so that people stop overfishing wild fish
- overfishing of wild fish has disrupted ecosystems

31
Q

how does introducing non indigenous species reduce biodiversity?

A
  • can happen intentionally for food or hunting (to control and reduce the number of species that have gotten out of control) or can be introduced unintentionally, either way causes issues for indigenous species
  • non indigenous species will compete with indigenous ones for resources like food and shelter, if they are better adapted at getting these they could out compete the indigenous species making them decrease in numbers and die
  • non indigenous species can also introduce new diseases to a habitat, infecting and killing lots of indigenous species
32
Q

what are 2 ways humans can benefit biodiversity?

A
  1. reforestation
  2. conservation schemes
33
Q

what is reforestation and how does it increase biodiversity?

A
  • when land where a forest previously stood in replanted to form a new forest
  • forests generally have high biodiversity because they have a wide variety of trees and plants, these in turn provide food and shelter for lots of different animal species
  • deforestation reduces this biodiversity by removing these trees, but reforestation restores this with a variety of tree species for more biodiversity
34
Q

what is a conservation scheme and how does it increase biodiversity

A
  • helps protect biodiversity by preventing endangered species from dying out and protecting their natural habitats
  • you can protect species in safe spaces outside of their natural habitat eg. zoos
  • introduce captive breeding programmes to increase numbers
  • using seed banks to store and distribute the seeds of rare and endangered plants
35
Q

what are the benefits to maintaining biodiversity?

A
  1. areas with greater biodiversity can recover faster from natural disasters
  2. protects human food supply
  3. minimal damage to food chains, if one species becomes extinct all the organisms in the chain will be affected, conserving one species helps others to survive
  4. providing future medicines from undiscovered plant species
    5, culture- individual species could be important to cultural heritage
  5. ecotourism- more people will spend money to visit biodiverse areas, money can be used for conservation work, also provides employment
36
Q

what is recycling?

A

this is when materials are recycled through both the biotic and abiotic components of an ecosystem
eg. plants in take in oxygen and co2, turn these into complex compounds, these are passed along the food chain, while this happens elements become recycled as the waste products (poop and dead animals) are broken down by decomposers and the elements return back into the atmosphere

37
Q

describe how the carbon cycle occurs.

A
  1. photosynthesis will occur and plants will take in the co2 from the atmosphere to make biological molecules like proteins and glucose (a carbon compound which makes up the biomass)
  2. the co2 could then either pass back into the atmosphere by respiration or it could be passed onto animals via the food chain, these animals will also release co2 via respiration
  3. these plants and animals will eventually die and decompose, when they decompose they’re broken down by micro organisms, these decomposers release co2 back into the air via microbial respiration
    - if they dont decompose aerobically they will turn into fossil fuels which can be burnt by humans and release co2
38
Q

describe the water cycle.

A
  • energy from the sun makes water evaporate from the land and sea turning it into water vapour, water can also evaporate via transpiration
  • warm water vapour is carried upwards by warm air rising and as it gets higher up it cools and condenses to form clouds
  • water falls from the clouds as precipitation onto land where it provides fresh water for plants and animals
  • it can then drain back into the sea via lakes and rivers
39
Q

what is drought and why is it a concern?

A
  • drought is low rainfall causing dry conditions
  • this is an issue because we rely on precipitation for freshwater in order to drink
  • when there is drought you must use alternative methods to produce potable water
40
Q

what is desalination?

A
  • removal of salts from salt water
41
Q

describe thermal desalination.

A
  • distillation
  • water is boiled causing it to evaporate, water vapour will rise however salts will not as they will have higher boiling points, this steam then travels through a tube and it will condense back into pure water
42
Q

what is reverse osmosis?

A
  • modern method of desalination
    1. salt water is treated to remove solids
    2. at very high pressure it is placed in a vessel containing a partially permeable membrane
    3. this pressure causes water molecules to move in the opposite direction of osmosis. in regular osmosis it will go from a high water conc to a lower water conc. but also a low salt conc. to high salt conc. THIS IS REVERSED TO high salt conc to low salt conc
43
Q

describe the nitrogen cycle.

A
  1. nitrogen gas in the air is converted into nitrates by nitrogen fixing bacteria
  2. these nitrates and absorbed by plants to make amino acids which are then passed into animals via the food chain
  3. the animals will produce urea but both the plants and animals will eventually die
  4. this means that nitrogen will remain in their waste products and remains
  5. decomposing bacteria will turn this nitrogen into ammonia
  6. nitrifying bacteria can turn this ammonia back into nitrates all over again
    - however denitrifying bacteria can break down nitrates back to nitrogen gas which returns into the air
44
Q

why do plants need nitrogen?

A
  • nitrogen is an important soil nutrient however plants cannot directly absorb this from the air. this is why nitrogen fixing bacteria (found in the soil) will convert the nitrogen into nitrates
  • nitrates can be absorbed by plants to make amino acids
  • high level of nitrates allow crops to grow faster, however overtime levels of nitrates fall as crops absorb it and become harvested rather than being decomposed, giving no way for it to be recycled back into the soil
45
Q

what are the types of bacteria involved in the nitrogen cycle?

A
  • decomposers
  • nitrifying bacteria
  • nitrogen fixing bacteria
  • denitrifying bacteria
46
Q

what do decomposers do in the nitrogen cycle?

A
  • turn nitrogen into from waste and dead organisms into ammonia
47
Q

what does denitrifying bacteria do in the nitrogen cycle?

A
  • turns nitrates back into nitrogen
48
Q

what does nitrogen fixing bacteria do in the nitrogen cycle?

A
  • turns nitrogen into nitrates
49
Q

what does denitrifying bacteria do?

A
  • turns nitrates back into nitrogen
50
Q

how do farmers increase the amount of nitrates in soil?

A
  • crop rotation
  • fertilisers
51
Q

what is crop rotation?

A
  • instead of continuously growing the same crops every year, different crops are grown in a cycle
  • one type of crop within this cycle will usually be a nitrogen fixing crop which helps put nitrates back into the soil
52
Q

what are fertilisers?

A
  • spreading compost or animal manure recycles the nutrients, returning them to the soil through decomposition
  • artificial ones can also be used that contain nitrates however they are very expensive.

Biology (9 decks)

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