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Green > 6.3.1: Ecosystems > Flashcards

6.3.1: Ecosystems Flashcards

1
Q

Define population

A

Group of organisms of the same species living in the same habitat

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2
Q

Define habitat

A

Part of an ecosystem where particular organisms live

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3
Q

Define community

A

All the populations of different species in the same area at the same time

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4
Q

Define ecosystem

A

A community of the living and non-living components of an environment

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5
Q

Define niche

A

An organism’s role within an ecosystem including position in the food web and it’s habitat

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6
Q

Define carrying capacity

A

The maximum population size an ecosystem can support

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7
Q

Give 3 features of an ecosystem

A
  • Dynamic ( constantly changing )
  • Vary in size e.g. rock pool, playing field and large tree
  • Influenced by biotic and abiotic factors
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8
Q

Give 2 examples of biotic factors

A

Predators

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9
Q

Give 3 examples of abiotic factors

A

Temperature, rainfall and pH

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10
Q

Define biotic

A

Living components of an ecosystem

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11
Q

Define abiotic

A

Non-living components of an ecosystem

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12
Q

Explain the biotic and abiotic factors of rock pools

A

Abiotic: Influenced by tides and low tides mean more extreme abiotic conditions such as temperature and salinity
Biotic: Seaweed (producer) as food source for consumers meaning there can be competition between species for resource

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13
Q

Explain the biotic and abiotic factors of a playing field

A

Biotic: Grass (producer) may attract organisms as a food source which could create competition
Abiotic: Rainfall can lead to water logging which limits plant growth and food sources.

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14
Q

Explain the biotic and abiotic factors of a large tree

A

Abiotic: Drought conditions from low rainfall can limit the tree growth and cause tree death
Biotic: Caterpillars eat leaves/use as food source which can limit tree growth and cause tree death

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15
Q

Define producer

A

An organisms that produces organic molecules using sunlight energy

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16
Q

Define consumer

A

An organisms that eats other organisms

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17
Q

Define decomposer

A

An organism that breaks down dead or undigested organic material

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18
Q

Define trophic level

A

A stage in the food chain occupied by a particular group of organisms

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19
Q

Define biomass

A

Mass of living material

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20
Q

Define ecological efficiency

A

The efficiency of an energy transfer

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21
Q

How is energy stored in organisms

A

As biomass

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22
Q

What is the main route energy enters an ecosystem by ?

A

Photosynthesis

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23
Q

How can you experimentally measure biomass loss in a plant ?

A

Dry plant and weigh mass of plant to find changes overtime. Mass of dry mass of tissue per given area is biomass.

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24
Q

What is the equation for calculating biomass at each trophic level ?

A

Biomass of an organism x no. of organisms

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25
Q

What is the unit for biomass on land ?

A

gm-2

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26
Q

What is the unit for biomass in water ?

A

gm-3

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27
Q

Why is the measurement of biomass often unreliable ?

A
  • There is varying water content in fresh material
  • If dry mass of animal is used it will have been killed which is unethical
  • Small sample size may mean its not representative
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28
Q

What would increase the reliability of the measuring biomass experiment ?

A

Include calculations for all the organisms at each trophic level

29
Q

What id the overall unit for biomass and what does it allow for ?

A

KJm-2 yr -1

Allows for changes in photosynthesis and feeding patterns throughout year

30
Q

Give the equation for efficiency

A

(Biomass transferred / biomass intake ) x 100

31
Q

Give 3 reasons for the loss of energy throughout a food chain

A
  • Indigestible or inedible parts of plant/ animal such as bones
  • Undigested food is lost as urine or faeces which becomes available to decomposer
  • Energy transferred as heat due to respiration or movement
32
Q

Give some ways human activities manipulate the transfer of biomass

A
  • Restrict the movement and respiration of animals by keeping them in warm indoor pens so less energy wasted keeping warm and reduce energy transferred as heat
  • Give animals higher energy food to increase energy input so more energy is available for growth
  • Remove competition, predators and disease using herbicides and fungicides
  • Provide optimal conditions for growth using controlled greenhouses and fertilisers
33
Q

Define gross production

A

Total solar energy that plants convert to organic matter

34
Q

Define net production

A

Energy available to next trophic level following energy released by plants during repiration

35
Q

What is the calculation for net production ?

A

Gross production - respiratory losses

36
Q

Why is only a small % of sunlight converted to chemical energy ?

A
  • Some energy transmitted straight through leaf
  • Energy is released by respiration
  • Energy is reflected
  • Energy is the wrong wavelength
37
Q

Give a positive and a negative of human activities manipulating the transfer of biomass

A
  • More food produced/ higher yield in a shorter space of time so higher profit
    HOWEVER
  • Ethical issues of restricting natural behaviour and causing distress for animals in intensely reared conditions
38
Q

Why do plants and animals need nitrogen ?

A

To make proteins and nucleic acids (DNA and RNA )

39
Q

Why are bacteria required within the nitrogen cycle ?

A

To convert atmospheric nitrogen so it can be usable

40
Q

What other ways can nitrogen enter the atmosphere ?

A

Lightning or artificial fertilisers which are manufactured using the haber process

41
Q

What type of bond is between 2 nitrogen atoms ?

A

Triple bond

42
Q

Which type of bacteria are involved in nitrogen fixation ?

A

Rhizobium (found in root nodules of leguminous plants)

Azotobacter (Free living in soil)

43
Q

What happens during nitrogen fixation ?

A

N2 in atmosphere is converted to NH3 and NH4+ ions

44
Q

What is unique about rhizobium ?

A

It is a mutualistic bacteria which means it has a mutualistic relationship to provide the plant with nitrogen compounds and the plant provides the bacteria with carbohydrates.

Adaptation meaning that plants containing this bacteria need to absorb fewer nitrogen-containing compounds because they already have ammonia around them in the roots of the plant

45
Q

Which bacteria is involved in ammonification ?

A

Saprotrophic bacteria (decomposes)

46
Q

What happens during ammonification ?

A

Nitrogen containing proteins, nucleic acids and vitamins (and animal waste) in dead organisms are broken down to form ammonia and ammonium compounds

47
Q

Which bacteria are involved in nitrification ?

A

Nitrosomonas and nitrobacter

48
Q

What happens during nitrification ?

A

Nitrosomonas oxidise ammonia and ammonium compounds to nitrate ions in soil NO2-

Nitrobacter oxidise NO2- ions to nitrate ions NO3-

49
Q

Which bacteria are involved in denitrification ?

A

Denitrifying bacteria

50
Q

What is a feature of denitrifying bacteria ?

A

They require anaerobic conditions such as waterlogged soil

51
Q

What happens during denitrification ?

A

NO3- in soil is converted to N2 gas

52
Q

Why do plants need carbon in CO2 ?

A

To make glucose

53
Q

What can an imbalance in the carbon cycle lead to ?

A

Ocean acidification and global warming as deforestation and burning too many fossil fuels means less CO2 is used in photosynthesis whilst more is produced in combustion

54
Q

What is the role of photosynthesis in the carbon cycle ?

A

Plants absorb carbon from CO2 in the atmosphere to photosynthesise and fix carbon into carbohydrates which can be ingested by animals or become carbon compounds in plant tissue

55
Q

What is the role of respiration within the carbon cycle ?

A

Carbon is returns to the air or ocean by all living organisms which respire and convert carbon in carbohydrates back to CO2

56
Q

What is the role of decomposition within the carbon cycle ?

A

When organisms die or excrete the carbon is broken down into CO2 by decomposers who respire using the carbohydrates within dead/waste material

57
Q

What is feeding on dead organic matter called ?

A

Saprobiontic nutrition

58
Q

Give a physical effect of cycling within the carbon cycle

A

CO2 can dissolve directly into oceans and be physically transported by ocean currents where is remains before returning to the surface and being released

59
Q

Give 2 chemical and physical effects of cycling within the carbon cycle

A
  • Carbon returned to the atmosphere from rocks being drawn down into Earth’s crust by the movement of tectonic plates. Rocks undergo chemical changes and release CO2 which is returned to atmosphere by volcanoes
  • Rocks become land and are weathered chemically by rainwater or physically by roots and animals causing mineral ions to combine with carbon compounds in the ocean to form CaCO3 which can be used for shells
60
Q

Define (primary) succession

A

The change in an ecological community overtime

61
Q

What is each stage of succession called ?

A

A seral stage

62
Q

Give the steps of primary succession

A

1) Spores and seeds blown by the wind land on a surface and grow
2) Pioneer species are adapted to survive in harsh abiotic conditions and colonise this new land surface such as bare rock and sand. When they die they decompose and change/improve the abiotic conditions by forming basic soil and a layer of hummus
3) Mosses and smaller plants can survive and further increase the depth and nutrient content of soil
4) Process of improving abiotic conditions increases and each new species changes the environment so it becomes less suitable for the previous species meaning they are out competed by new colonising species
5) Biodiversity is increased until it reaches a climax community which is dominated by trees

63
Q

What is deflected succession ?

A

Where human activities prevent the progress of succession and stop normal climax communities developing

64
Q

What is the term for when succession is stopped and cannot resume ?

A

Plagio-climax

65
Q

Give an example of deflected succession

A

Regularly mown grass as it won’t develop woody plants as growing points are cut off and larger plants can’t establish themselves

66
Q

What are the practical ways to investigate ecosystems ?

A
  • Transect to investigate distribution of plant species
  • Frame and point quadrat to investigate plant populations
67
Q

What must you ensure when investigating ecosystems practically ?

A
  • Calculate % cover
  • Use random sampling with repeats
  • Use an identification tool key to identify species
68
Q

Define climax community

A

Community which is stable with no further succession

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