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Edexcel GCSE Biology > SB9 - Ecosystems and Material Cycles ✓ > Flashcards

SB9 - Ecosystems and Material Cycles ✓ Flashcards

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1
Q

SB9a - Define an Ecosystem

A

An ecosystem is all the organisms and the habitat in which they live

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2
Q

SB9a - Define a Community

A

All the organisms that live and interact in an ecosystem

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3
Q

SB9a - Define a population

A

The total amount of one species in a population

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4
Q

SB9a - Define Interdependence

A

When organisms depend on each other for resources within an ecosystem.

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5
Q

SB9a - How do you estimate population size using quadrat experiments?

A

Population size

=

(total size of area where organism lives ÷ total area of quadrats) x

number of organisms in all quadrats

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6
Q

SB9b - Once a plant has taken in energy from the sun, where does the energy get transferred to?

A

Much is transferred to plant biomass. The rest is transferred to the environment by heating during the life processes.

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7
Q

SB9b - Why isn’t energy transferred to surroundings by heating useful?

A

Other organisms can’t use it.

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8
Q

SB9b - Why does a secondary consumer need to eat more then a primary consumer?

A
  • Only some of the energy from the PC’s diet is converted to biomass and the rest is wasted by transferring to heat in the surroundings.
  • Therefore to get the same amount of energy, the SC will need to eat more.
  • This is why there is a limit to the size of a food chain.
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9
Q

SB9b - What happens to the biomass at each trophic level (on a pyramid of biomass)

A

It reduces significantly.

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10
Q

SB9b - Why is a pyramid of biomass usually bottom heavy?

A

At each level more energy is being wasted so at each level there is less energy to be used and less biomass can be produced.

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11
Q

SB9b - Why is there a maximum limit to how many trophic levels a food chain can have?

A

Since there is less biomass at each level, after a certain level, the amount of the lower species you’d have to consume would be too high.

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12
Q

SB9c - What is the distribution of organisms?

A

Where organisms can be found in a food chain

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13
Q

SB9c - What is an abiotic factor?

A

A non-living factor that affects organisms

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14
Q

SB9c - Name some abiotic factors.

A
  • Abundance of Water
  • Light intensity
  • Temperature
  • Wind
  • Pollutants
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15
Q

SB9c - What about an organisms may mean that they are affected by abiotic factors.

A
  • An organisms adaptations.
  • If an adaptation is specific to a condition then an abiotic factor that affects that condition will mean that the organism is not longer adapted to their conditions
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16
Q

SB9cCP - Quadrats and transects: Compare knowledge of SB9c to this CP.

A

Use CP book for revision

[Will add before real exam]

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17
Q

SB9d - What are biotic factors?

A

The organisms in an ecosystem that affect each other.

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18
Q

SB9d - What are the two main biotic factors?

A
  • Competition
  • Predation
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19
Q

SB9d - Describe what a predator - prey cycle is.

A
  • When a predator eats their prey the population of prey decreases.
  • Now there isn’t enough food for the predator so their population decreases
  • Now that there is less predation, the prey’s population can increase again
  • Now there is more food for the predator so their population can increase again.
  • This goes on and so the predator is affected slightly after the prey
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20
Q

SB9d - Explain why a predator - prey cycle may not be seen in larger ecosystems with more biodiversity.

A
  • In an ecosystem with more biodiversity, a predator doesn’t prey on one species and a prey isn’t predated by one species.
  • This means that it is unlikely that one species will ever cause another’s population to decrease and if so, this wouldn’t affect the other species.
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21
Q

SB9d - How can adding just one new species to an ecosytem be benefical to the biodiversity?

A
  • New species provide more habitats and/or food for many species.
  • For example in yellowstone when wolves were (re)introduced, this decreased elk numbers increasing beavers and increasing the amount of dams which altogether promoted the biodiversity of the ecosystem
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22
Q

SB9e - Name indicator species for levels of water pollution.

A
  • High levels of pollution:
    • Sludgeworm
    • Bloodworm
  • Low levels of pollution:
    • Stonefly nymph
    • Dragonfly nymph
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23
Q

SB9e - Name indicator species for levels of air pollution in terms of sulfur dioxide concentration

A
  • Lower levels of sulfur:
    • Blackspot fungus on roses
  • Higher levels of sulfur:
    • Lichens such as Lecanora conizaeoides
24
Q

SB9d - Why is reforestation an effectivce way of preserving biodiversity?

A
  • Trees provide habitats and food for many species.
  • More trees is an effective way of making an ecosystem suitable for more species.
25
Q

SB9e - Why may indicator species not be effective?

A

They don’t give numerical/quantitative results and so aren’t fully accurate and comparable especially as both air and water pollution can be numerically measured.

26
Q

SB9f - What is a parasite?

A

An organism in a feeding relationship with another organism usually harmful to that other organism. e.g Lice and tapeworms

27
Q

SB9f - What is a mutualist (symbiote)

A

An organism in a realtionship with another organism which is beneficial to both as they each provide something to each other. (e.g. bees and flowers or oxpecker and zebras)

V̶e̶n̶o̶m̶ ̶i̶s̶ ̶a̶ ̶f̶i̶c̶t̶i̶o̶n̶a̶l̶ ̶c̶h̶a̶r̶a̶c̶t̶e̶r̶ ̶a̶p̶p̶e̶a̶r̶i̶n̶g̶ ̶i̶n̶ ̶A̶m̶e̶r̶i̶c̶a̶n̶ ̶c̶o̶m̶i̶c̶ ̶b̶o̶o̶k̶s̶ ̶p̶u̶b̶l̶i̶s̶h̶e̶d̶ ̶b̶y̶ ̶M̶a̶r̶v̶e̶l̶ ̶C̶o̶m̶i̶c̶s̶,̶ ̶c̶o̶m̶m̶o̶n̶l̶y̶ ̶i̶n̶ ̶a̶s̶s̶o̶c̶i̶a̶t̶i̶o̶n̶ ̶w̶i̶t̶h̶ ̶S̶p̶i̶d̶e̶r̶-̶M̶a̶n̶.̶ ̶T̶h̶e̶ ̶c̶h̶a̶r̶a̶c̶t̶e̶r̶ ̶i̶s̶ ̶a̶ ̶s̶e̶n̶t̶i̶e̶n̶t̶ ̶a̶l̶i̶e̶n̶ ̶S̶y̶m̶b̶i̶o̶t̶e̶ ̶w̶i̶t̶h̶ ̶a̶n̶ ̶a̶m̶o̶r̶p̶h̶o̶u̶s̶,̶ ̶l̶i̶q̶u̶i̶d̶-̶l̶i̶k̶e̶ ̶f̶o̶r̶m̶,̶ ̶w̶h̶o̶ ̶r̶e̶q̶u̶i̶r̶e̶s̶ ̶a̶ ̶h̶o̶s̶t̶,̶ ̶u̶s̶u̶a̶l̶l̶y̶ ̶h̶u̶m̶a̶n̶,̶ ̶t̶o̶ ̶b̶o̶n̶d̶ ̶w̶i̶t̶h̶ ̶f̶o̶r̶ ̶i̶t̶s̶ ̶s̶u̶r̶v̶i̶v̶a̶l̶.̶

28
Q

SB9g - Why is fish farming needed and what are the problems with it?

A
  • About 17% of the world’s protein consumption is fish based.
  • However overfishing leads to loss of certain fish species.
  • So the solution is to farm fish.
  • Since so many fish are kept in a small space, all their uneaten food and faeces sink to the bottom creating a harmful atmosphere alowing parasites and disease to spread easily throughout fish.
29
Q

SB9g - How may adding non-indigenous species to an ecosystem negatively effect biodiversity?

A
  • After humans have added new species to an ecosystem, these species may outcompete native species for resources meaning the native species reduce in numbers affecting the ecosystem.
30
Q

SB9g - Describe the process of eutrophication.

A
  • Fertiliser is added
  • Heavy rain washes fertilisers off dissolving nitrates and phosphates into soil water
  • If plants take up the nitrates and phosphates and there is still some remaining this gets washed into streams and rivers
  • The high concentration of fertilising substances encourages rapid growth of algae and plants on water surface
  • Surface plants block sunlight and so plants in the water die as they stop photosynthesising
  • The decomposing bacteria increases in numbers and consumes more oxygen
  • Oxygen concentration in water decreases
  • Aquatic animals die due to anoxic water
31
Q

SB9h - What are the benefits and limitations of keeping endagered species in captivity?

A

Pros:

  • Ensure they’re safe
  • Provide them with all needed resources meaning other organisms can’t outcompete them

Cons:

  • They may become habitualised
  • Inbreeding may be required causing many genetic problems
32
Q

SB9h - Why is it important to preserve biodiversity?

A
  • Many organisms are interdependant and all the organisms play an important role in each other’s survival
  • Areas with larger biodiversity have a greater chance of recovering form natural disasters as not every organism will be affected
  • As humans we require plants and animals for many thing (e.g medicine) and so it is important that we preserve all the species we can for when our needs change
33
Q

SB9h - Why is conservation crucial?

A

To ensure that species don’t become extinct

34
Q

SB9i - What is food security?

A

Having access to sufficient safe and healthy food at all times.

35
Q

SB9i - What is the difference in the trends of food consumption between first and third world countries.

A

Wealthier people tend to want:

  • More food
  • More meat and fish produce in their diet

Good thing I’m dirt poor I gueabhfdlbhsl vjl lnsk

36
Q

SB9i - Why is sustainability an issue in agriculture?

A
  • The amount of fertiliser used ha sincreased as to increase the yield of crops.
  • However the process to create fertilisers release carbon dioxide.
  • Additionally, eutrophication can be a problem.
37
Q

SB9i - How can climate change promote the spread of new diseases?

A
  • Climate change can move pests and pathogens into new areas.
  • For example if there is a pest that is a vector for a disease but the pest can only survive in warm conditions, as climate change increases the global temperature, they can go to more places.
38
Q

SB9i - Why is meat an inefficient source of protien?

A

The amount of land and energy taken up to farm and produce meat as a food product is much more than crops. 15 times more protein is produced from soy bean than animals in the same amount of land.

39
Q

SB9i - What are the pros and cons of biofuel.

A

Pros:

  • Less CO2 emisison
  • Crops are easy to obtain

Cons:

  • Land could be used to grow food instead
  • May not be sustainable
40
Q

SB9j - Describe the process of the water cycle.

A
  • Water evapourates from lakes and oceans to form water vapour
  • As water vapour rises it cools, condenses and forms clouds
  • Once cloud droplets get too large precipitaiton occurs
  • Some water runs off the surface directly into the lakes and rivers
  • Other water is percolated
  • some of this moves through rocks and soils till it reches lakes and rivers
  • the rest is taken up by plants through transpiration and is evapourated directly
41
Q

SB9j - Describe ways water may be made potable.

A
  • Solar stills
  • Nets
  • Distillation
  • Desalination in general. (obtaining pure water from salty water)
  • Treatment with chemicals and filteration
42
Q

SB9j - Describe the main features fo the carbon cycle.

A
  • Plants respire and photsynthesise both releasing and taking in carbon
  • Animals feed off plants taking in carbon to their biomass and release it through respiration
  • When organisms die, their biomass is compressed into fossil fuels which release carbon through combustion
  • Soft tissue in the dead organism is eaten by decomposers which release carbon through respiration
43
Q

SB9j - What are the absorbed carbon molecules used for in plants?

A

They are made into carbon compounds like glucose. some may be used for growth as they are converted into biomass.

44
Q

SB9j - How does carbon travel through an animal?

A
  • The carbon is taken in as carbohydrates fats and protiens in another organism and excreted through faeces.
  • Some may be digested and used as biomass in tissue
45
Q

SB9k - Describe the main features of the nitrogen cycle.

A
  • Nitrogen in the air is taken into the soil by nitrgoen fixing bacteria and by lightning
  • Or the opposite way round by breakdown of soil bacteria.
  • Plants absorb nitrates in the soil through their roots or through nitrogen fixing bacteria in root nodules
  • Animals feed on plants takin gin nitrogen
  • Death and excretion of animals means decomposers such a soil bacteria break down the protien and urea to soil nitrates
46
Q

SB9k - Why is nitrogen so important for organisms?

A

Nitrogen is used to from protiens and DNA and this allows organisms to grow.

47
Q

SB9k - Why can’t plant absorb nitrogen form the air?

A

Plants absorb nitrogen through the soluble substances taken up by their root hair cells, thus nitrogen must be in a soluble form to be absorbed by plants.

48
Q

SB9k - Why are decomposers important to farmers?

A

They maintain soil fertility by breaking down substances into nitrogen.

49
Q

SB9k - How may farmers maintin soil fertility in their fields?

A
  • Spreading in manure around the field.The animal waste in this can be broken down to form nitrogen
  • Using fertilisers
  • Using plants that have root nodules and/or digging these roots in
50
Q

SB9k - What is the purpose of root-nodules?

A

They are parts of a plant that contain protected soil fixing bacteria which can produce soluble nitrogen compounds in the soil. (they are in a mutualistic relationship)

51
Q

SB9k - What is crop roation and what is its purpose?

A
  • Rotating which crops are planted when in a ceratin area.
  • This means that the root nodules of one plant rotation make the soil more fertile and useful for the next crop planted increasing the next crop’s yield.
52
Q

SB9m - What do methods of food preservation rely on and why?

A
  • Reducing oxygen and water content as water and oxygen are needed for decomposers to respire and grow
  • Reducing temperature as this reduces the rate of reaction of decomposers
  • Irradiation of food packing as it kills decomposers
53
Q

SB9m - What is compost and why is it used?

A
  • Well-decayed parts of waste garden material.
  • This is used to help crop fertility
54
Q

SB9m -What are the ideal conditions for a crop heap and why?

A
  • Covered top to stop too mcuh rain from entering and too stop moisture and heat from leaving
  • Sides have openings to let oxygen in
  • This is as decomposers require both oxygen and water to respire and grow and higher temperature will increase rate of reaction
  • Compost heaps are turned every so often to ensure even decomposition
55
Q

SB9m - How do you calculate rate of decay?

A

Loss of measure of decay ÷ the time taken

(e.g 6g lost in 3 days means 6 ÷ 3 = 2g/day)

Edexcel GCSE Biology (11 decks)

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