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A level Biology > 6.3 Ecosystems, Populations and Sustainability > Flashcards

6.3 Ecosystems, Populations and Sustainability Flashcards

1
Q

What are some biotic factors experienced by a rock pool?

A
  • Food competition
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2
Q

What are some abiotic factors experienced by a rock pool?

A
  • Tides: pH, salinity, temperature
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3
Q

What are some biotic factors experienced by a playing field?

A
  • Food
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4
Q

What are some abiotic factors experienced by a playing field?

A
  • Rainfall
  • Sunlight
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5
Q

What are some biotic factors experienced by a large tree?

A
  • Deformation (removal of leaves)
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6
Q

What are some abiotic factors that can be experienced by large trees?

A
  • Low rainfall
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7
Q

What is the main way that energy enters an ecosystem?

A

Through photosynthesis

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8
Q

What do plants store energy as?

A

Biomass

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9
Q

What is biomass?

A

The mass of living material

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10
Q

How is energy transferred through the living organisms of an ecosystem?

A

By the organisms eating other organisms

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11
Q

What do food chains and webs show?

A

How energy is transferred through an ecosystem

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12
Q

Why isn’t all energy transferred to the next trophic level?

A

Because around 90%of available energy is lost in various ways

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13
Q

How is energy lost in trophic levels?

A
  • some energy isn’t taken in
  • Some energy is lost via respiration
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14
Q

Why is some of the available energy not taken in by organisms?

A
  • Plants can’t use all the light energy that reaches their leaves. Some is the wrong wavelength, some is reflected, and some passes straight through the leaves.
  • Some sunlight can’t be used because it hits parts of the plant that can’t photosynthesise I.e the bark.
  • Some parts of food aren’t eaten by organisms so the energy isn’t taken in
  • Some parts of food are indigestible so pass through organisms and come out as waste
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15
Q

What is the net productivity?

A

The amount of energy that is available for the next trophic level

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16
Q

What is the gross productivity?

A

The energy that is taken in

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17
Q

Net productivity =

A

Gross productivity- respiratory loss

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18
Q

Efficiency =

A

Biomass transferred/ biomass intake X 100

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19
Q

What is the carbon cycle?

A

How carbon moves through living organisms and the non-living environment

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20
Q

Give the 8 stages of the carbon cycle

A

1) Photosynthesis
2) Respiration by plants
3) Feeding
4) Death and waste
5) Respiration by animals
6) Decomposition of dead animals
7) No Decomposition after death , leading to the formation of fossil fuels.
8) Combustion of fossil fuels

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21
Q

What is called when decompsoers feed on dead organic matter?

A

Saprobiontic nutrition

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22
Q

What are rocks such as limestone and chalk mainly composed of ?

A

Calcium carbonate

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23
Q

what do plants and animals need nitrogen to make?

A

proteins and nucleic acids

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24
Q

what does the nitrogen cycle show?

A

how nitrogen is converted into a useable form and then passed on between different living organisms and the non-living environment

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25
Q

What are the 4 main processes of the nitrogen cycle?

A
  • Nitrogen fixation
  • Ammonification
  • Nitrification
  • Denitrification
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26
Q

what is nitrogen fixation?

A

where nitrogen gas is turned into Ammonium(NH4+) by bacteria Rhizobium and Azotobacter

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27
Q

where is rhizobium found?

A

in root nodules of legumous plants

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28
Q

where is azotobacter found?

A

in the soil

29
Q

what is ammonification?

A

when nitrogen compounds from dead organisms are turned into ammonia by decomposers, which go on to form ammonium ions

30
Q

what is nitrification?

A
  • when ammonium ions in the soil are changed into nitrogen compounds that can then be used by plants as nitrates.
  • first nitrifying bacteria called Nitrosomonas change ammonium ions into nitriles.
  • then nitrobacter change nitrites into nitrates
31
Q

what is denitrification?

A

when nitrates in the soil are converted into nitrogen gas by denitrifying bacteria. this happens under anaerobic conditions

32
Q

what are some other ways that nitrogen enters the atmosphere?

A
  • Lightning
  • artificial fertilisers
33
Q

what is succession?

A

the process by which an ecosystem changes over time

34
Q

what re the 2 types of succession?

A

primary succession and secondary sucession

35
Q

where does primary succession happen?

A

on land that’s been newly formed or exposed

36
Q

where does secondary succession happen?

A

on land that’s been cleared of all the plants, but where the soil remains

37
Q

what’s an example of a type of land that undergoes primary succession?

A

where a volcano has erupted to form a new rock surface, or where the sea level has dropped, exposing a new areas of land

38
Q

what’s an example of a type of land that undergoes secondary succession?

A

after a forest fire, or where a forest has been cut down by humans

39
Q

Give some examples of biotic factors

A
  • Predation
  • Competition (inter-specific) for space, food, water, light etc.
  • ## Disease
40
Q

Give some examples of abiotic factors

A

Availability of water
Light
Temperature
Turbidity (‘cloudiness’) of water
Humidity
pH
Salinity
Soil composition

41
Q

what do saprobionts do?

A

they secrete enzymes onto their food (dead organisms and waste material), which then digest the material externally

41
Q

what are the stages of primary succession?

A
  • Pioneer species colonise the new land
  • The pioneer species change the abiotic conditions by dying and decomposing. This forms a basic soil
  • New organisms can move in and grow. When they die and decompose, the soil becomes deeper and richer in minerals.
  • Larger plants, like shrubs, grow in the deeper soil.
  • As more plants move in they create more habitats, so more animals move in.
42
Q

what happens after primary succession is complete?

A

a climax community is created

43
Q

what is a climax community?

A

where the ecosystem is supporting the largest and most complex community of plants and animals it can, and the community won’t change very much

44
Q

Give an example of primary succession (bare rock to woodland)

A
  • Pioneer species, such as lichens, colonise the rocks.
  • The lichens dies and decompose, helping to form a thin soil. This allows species such as mosses to grow
  • Larger plants that need more water can move in as the soil deepens. i.e small trees and shrubs. The soil continues to deepen as the larger plants die and are decomposed.
  • Shrubs, ferns, and small trees begin to grow and they outcompete the smaller plants
  • The soil finally becomes deep and rich in nutrients enough to support large trees. These become the dominat species and a climax community is formed
45
Q

what is a plagioclimax?

A

when successon is stopped artificially

46
Q

what is deflected succession?

A

when succession is prevented by human activity

47
Q

what are some ways succession can be deflected?

A
  • through mowing
  • grazing
  • managed burnings
48
Q

Populations and Sustainability

A
49
Q

what is the population size?

A

the total number or organisms of one species in a habitat

50
Q

what causes the population size to vary?

A

both biotic and abiotic factors

51
Q

what is the carrying capacity?

A

the maximum stable population size of a species that an ecosystem can support

52
Q

what is predation?

A

where a predator kills and eats prey

53
Q

what are the population sizes of predators and prey controlled by?

A

negative feedback

54
Q

is it true that limiting factors stop the population size of a species from increasing?

A

yes

55
Q

do limiting factors determine the carrying capacity of an ecosystem?

A

yes

56
Q

what is conservation?

A

conservation is the protection and management of ecosystems so that natural resources can be used without them running out

57
Q

for what reasons is the conservation of ecosystems important?

A
  • Economic reasons
  • Social reasons.
  • Ethical reasons
58
Q

what are the economic reasons for why conservation of ecosystems is important?

A
  • Ecosystems provide resources for a lot of things humans need i.e drugs and food.
  • These resources are economically important and so if these ecosystems aren’t conserved, the resources will be lost and this will result in a loss of money
59
Q

what are the social reasons for why conservation of ecosystems is important?

A
  • Looking at certain ecosystems makes people happy because they’re attractive to look at
60
Q

what are the social reasons for why conservation of ecosystems is important?

A
  • Some people think it’s morally right to conserve ecosystems
61
Q

what is preservation?

A

the protection of ecosystems so that they’re kept exactly as they are

62
Q

how can fishing provide resources in a sustainable way?

A
  • Using fishing quotas
  • Controlling mesh size or nets
63
Q

what are fishing quotas?

A
  • limits to the amount of certain fish species that fishermen are allowed to catch
64
Q

what does the eu common fisheries policy state?

A

it regulates the amount of fish each country can take and where they’re allowed to take them from

65
Q

Define ‘producer’

A

Photosynthesises and produces its own food

66
Q

Define consumer

A

Feeds on other ogranisms

67
Q

Define trophic level

A

A stage in a food chain

68
Q
A

A level Biology (7 decks)

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