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Biology > Ecosystems and Sustainability > Flashcards

Ecosystems and Sustainability Flashcards

1
Q

Define Ecosystem

A

A group of living and non-living components which occur together and the interrelationships between them

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2
Q

Define Habitat

A

A place where organisms live

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3
Q

Define Population

A

All the individuals of a species in one place

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4
Q

Define Community

A

All the individuals of all species in one place

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5
Q

Define Niche

A

The role an organism plays in an ecosystem

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6
Q

What does the niche of an organism involve?

A

What it feeds on, excretes, how it reproduces. It is impossible for two organisms to occupy the same niche

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7
Q

What do all ecosystems have in common?

A

They are all dynamic systems, meaning that they are always changing

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8
Q

Define ‘biotic factor’

A

Living components in an ecosystem

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9
Q

Give examples of biotic factors

A

Disease
Food (Prey/Grazing)
Competition (Intraspecific/Interspecific)
Trampling

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10
Q

What is the difference between interspecific and intraspecific competition

A

Interspecific is competition between members from different species compete for a shared and limited resource.
Intraspecific competition between individuals from the same species over a limited resource (such as a mate)

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11
Q

Define ‘abiotic factor’

A

Non-living components of an ecosystem

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12
Q

Give examples of abiotic factors

A 
Water availability
Mineral availability
Space
Light
Temperature
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13
Q

Define Producer

A

Organisms that convert light energy (photoautotroph) or chemical energy (chemoautotroph) into chemical chemical energy which is then available to consumers

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14
Q

Define Consumer

A

Living organisms that feed on other organisms. these include Herbivores, Carnivores and Omnivores.

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15
Q

Define Decomposer

A

Organisms that feed on dead organic matter, releasing molecules, minerals and energy that then become available to other living organisms in that ecosystem
eg. Bacteria and Fungi

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16
Q

What is a saphrotroph

A

Organisms that secrete enzymes onto the dead organic matter. Digestion takes place outside the decomposer and the digested material is then taken in by the decomposer, although some remains in the ecosystem

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17
Q

Define trophic level

A

The level at which an organism feeds in a food chain

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18
Q

Why does the amount of energy at each trophic level decrease?

A

Photosynthesis/Digestion is not 100% efficient at creating chemical energy
Energy lost through movement, excretion, respiration
Not all parts of plant/animal are edible for consumer

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19
Q

Why is there far less individuals at a higher trophic level?

A

Not all energy is transferred to the next level

Larger individuals need more energy each to create the whole organism fully grown (usually)

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20
Q

What is a pyramid of biomass?

A

A visual representation of the total biomass of a species in a habitat from consumer to producer. Biomass is the dry mass of an individual multiplied by the number of individuals

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21
Q

What are the problems with pyramids of biomass?

A

Data calculation is destructive as it need to be heated in an oven to eliminate the water.
Not all biomass has the same energy per unit of mass.
Data now has to be compared to past data meaning it is less accurate.

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22
Q

What is a pyramid of energy?

A

A visual representation of the total energy of a species in a habitat from consumer to producer.

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23
Q

How is the total energy of an individual calculated?

A

Using a calorimeter where the dry mass is burnt to heat a known volume of water. This is very destructive however so previous data is now used.

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24
Q

Define Productivity

A

The rate of energy flow through each trophic level

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25
Q

Energy transfer from SUN to PRODUCER

A

Most energy is not incorporated into the plant
99% of light is reflected off the plant
only certain wavelengths can be absorbed
some light is absorbed by non-photosynthetic parts (bark)
Passes through leaf (misses chlorophyll/chloroplasts)
Some energy is heat which is used in evaporation/respiration

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26
Q

Energy transfer from PRODUCER to #1 CONSUMER

A

Difficult to digest so energy is wasted
Micro-organisms in gut use some of the energy
Some material cannot be eaten/digested at all
Some food lost in excretion due to <100% digestion efficiency
Some energy used in respiration
Some energy lost as heat
Only a small proportion of energy is used for growth (meaning it is available to the next trophic level)

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27
Q

Energy transfer from CONSUMER 1 to CONSUMER 2

A

Animal material digested much easier than plant material
Meat provides similar amino acids needed for consumer
Some energy lost in excretion, movement and respiration
Only small proportion of energy used for growth

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28
Q

Define ‘gross productivity’

A

Total energy received at trophic level

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29
Q

Define ‘net productivity’

A

Total energy left available to next trophic level

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30
Q

Define Succession

A

A natural directional change in species composition in a community of organisms over time

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31
Q

What is the difference between primary and secondary succession?

A

Primary succession is from bare earth/rock whereas secondary succession is from a disturbed/damaged habitat, often after a natural disaster such as a volcano eruption.

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32
Q

Define Sere

A

An intermediate stage in succession

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33
Q

Define Sere

A

An intermediate stage in succession

34
Q

Define ‘primary productivity’

A

The total amount of energy fixed by photosynthesis. It is the net flux of carbon from the atmosphere to plants, per unit time. It is a rate and may be measured in terms of energy per unit time, such as MJ/m^2/yr

35
Q

Define ‘net primary productivity’

A

The rate at which carbohydrate accumulates in the tissue of plants of an ecosystem and is measured in dry organic mass, such as Kg/ha/yr

36
Q

How can net primary productivity be calculated?

A

NPP = PP - respiratory heat loss

37
Q

What are the limitations of NPP?

A 
Light levels
Lack of water
Temperature
Lack of nutrients
Pests
Fungal diseases
Competition from weeds
38
Q

Hiw do humans deal with lack of light levels for plants?

A

They can plant the crops earlier, to extent the growing season, making the most of the available light.
They can grow them under artificial light in banks.

39
Q

How do humans deal with lack of water to crops?

A

Crops are irrigated so they get a man made source of water, as well as rain water.
Drought resistant strains of crops have been bred so that they need less water to produce a similar yield.

40
Q

How do humans deal with temperature as a limiting factor to crops?

A

Greenhouses can be built for the plants to grow in so the heat is trapped inside, raising the temperature.
An early plant of the crops also helps as then the lack of temperature (if there is one) has less of an effect.

41
Q

How do humans deal with temperature as a limiting factor to crops?

A

Greenhouses can be built for the plants to grow in so the heat is trapped inside, raising the temperature.
An early plant of the crops also helps as then the lack of temperature (if there is one) has less of an effect.

42
Q

How do humans deal with lack of nutrients to plants?

A

Crop rotation is used, where you grow a different crop in each field each year on rotation. This helps to replenish some of the nutrients that some plants need and others don’t.
Nitrogen fixing plants also help to make sure there is enough nitrogen for the next crop that will be planted there.

43
Q

How do humans deal with pests as a limitation to crop yields?

A

Pests remove biomass from the plant by eating them. Spraying with pesticides means the pests will die if they try to eat the plant but the plant itself remains unharmed.
Some plants have been bred to be pest resistant.

44
Q

How do humans deal with fungal diseases as a limitation to crop yields?

A

Fungal diseases and affect practically all of the parts of the plant involved in energy production. Farmers use fungicides so they the fungi cannot live off the plant without dying.
Some plants have been bred to be resistant to certain fungi.

45
Q

What ways do humans improve secondary productivity (crops to animals)?

A

Harvesting just before adulthood so only the most efficient part of the growth period is used.
Using steroids so more energy goes into growth (this has been outlawed).
Selective breeding is used to produce the breed with the fastest/most efficient growth rate.
Animals treated with antibiotics to avoid loss of energy to parasites and pathogens.
Keeping them still and warm means there is less loss of energy from respiration for movement, and more energy going to growth and protein production.

46
Q

What ways do humans improve secondary productivity (crops to animals)?

A

Harvesting just before adulthood so only the most efficient part of the growth period is used.
Using steroids so more energy goes into growth (this has been outlawed).
Selective breeding is used to produce the breed with the fastest/most efficient growth rate.
Animals treated with antibiotics to avoid loss of energy to parasites and pathogens.
Keeping them still and warm means there is less loss of energy from respiration for movement, and more energy going to growth and protein production.

47
Q

What is a pioneer community?

A

The first community/plants to grow in a habitat (usually on bare rock) such as algae and lichens.

48
Q

What is a climax community?

A

It is the final sere in succession, producing a stable community that cannot grow any further. In the UK, this would be woodland.

49
Q

How do saprotrophs feed?

A

They secrete enzymes onto dead waste which digest the material into small molecules. These molecules are then absorbed into the organism’s body where they can then be respired.

50
Q

Give examples of saprotrophs

A

Bacteria and Fungi

51
Q

What do saprotrophs have an important role in recycling and how do they do this?

A

They aer important in recycling nitrogen and carbon and do this by digesting and respiring the dead waste from plants and animals which would otherwise trap these in the ground

52
Q

What type of relationship do plants in the bean family have with what nitrogen fixing bacteria?

A

They have a mutualistic relationship with Rhizobium which live in the root nodules of those plants. The bacteria provide the plant with fixed nitrogen compounds and receive carbon compounds in return.

53
Q

Revise the Notrogen Cycle

A

Pg 202 and the A3 Nitrogen Cycle in noted

54
Q

Define Nitrogen Fixation

A

The conversion of nitrogen gas into a form which is usable by plants, such as nitrate or ammonium ions

55
Q

How do nitrifying bacteria get their energy?

A

By oxidising ammonium ions to nitrites and oxidising nitrites to nitrates. Oxygen needs to be present for this to happen so this only occurs in well-aerated soils.

56
Q

Why do denitrifying bacteria convert nitrates to nitrogen gas?

A

They use the nitrates and convert them back to nitrogen gas so they can use the oxygen in the molecule for respiration in areas which do not have much oxygen present.

57
Q

Define Carrying Capacity

A

The maximum population size that can be maintained over a period of time in a particular habitat.

58
Q

Define limiting factor

A

Where the rate of a natural process is affected by a number of factors, the limiting factor is the one whose magnitude limits the rate of the process. It is often the factor in shortest supply.

59
Q

What does the size of a population depend on?

A

The balance between the birth rate and death rate, and how long the balance has been going on for.

60
Q

What is the lag phase on a population time graph?

A

This is the phase where there may only be a few individuals in the population. This is the stage where they are acclimatising to the habitat so the rate of reproduction is low, as well as the death rate, so the overall population growth is low.

61
Q

What is the lag phase on a population time graph?

A

This is the phase where there may only be a few individuals in the population. This is the stage where they are acclimatising to the habitat so the rate of reproduction is low, as well as the death rate, so the overall population growth is low.

62
Q

What is the log phase on a population time graph?

A

This is the ‘boom’ phase in a populations growth, where the species has successfully acclimatised to the habitat and all resources are plentiful, resulting in a high reproduction rate and a low death rate.

63
Q

What is the stationary phase in a population time graph?

A

This the point where the population stops growing as it has reached, and sometimes surpassed the carrying capacity, so the death rate levels off with the birth rate, so the overall population stops increasing with very small fluctuations depending on the variations in the habitat.

64
Q

What are examples of limiting factors for population size?

A

Food, water, light, oxygen, nesting sites, shelter, predators.

65
Q

Define Competition

A

Competition occurs when resources, such as food and water, are not present in adequate amounts to satisfy the needs of all the individuals who depend on that resource.

66
Q

What is the relationshop between competition and reproduction?

A

As the intensity of competition increases, the rate of reproduction decreases due to there being less resources needed for survival.

67
Q

Define Intraspecific Competition

A

This happens between individuals of the same species. This is one of the main causes of survival of the fittest, as the individuals competing for survival will also be competing for the chance to mate, and pass on their genes.

68
Q

Define Intraspecific Competition

A

This happens between individuals of the same species. This is one of the main causes of survival of the fittest, as the individuals competing for survival will also be competing for the chance to mate, and pass on their genes.

69
Q

How does intraspecific competition affect population size?

A

It keeps it reasonably stable, because as the population increases, the competition increases, so the death rate increases/reproduction rate decreases because of this, meaning the overall population decreases and vice versa.

70
Q

Define Interspecific Competition

A

This is competition between individuals from two different species.

71
Q

What causes an increase in interspecific competition?

A

The more the niches of two species overlaps, then the higher the competition will be between those species.

72
Q

What are the outcomes of interspecific competition?

A

One species can become extinct due to the level of competition, or some species can become smaller than the other species and remain relatively constant.

73
Q

Define Coppicing

A

Cutting a tree trunk close to the ground to encourage new growth.

74
Q

Define Coppicing

A

Cutting a tree trunk close to the ground to encourage new growth.

75
Q

What is pollarding and why is it used?

A

A technique similar to coppicing but the cut is made higher up the tree so less wood is harvested. This is useful when there is a high population of animals who like to eat the new buds on the trunk, such as deer.

76
Q

What is rotational coppicing?

A

Dividing a wood into sections and only cutting one section every year to create a continuous supply of wood

77
Q

What is clear felling and why is it so damaging?

A

Clear felling involves cutting down all the trees in a certain area all at once so that there is a large harvest of wood in one go. This destroys habitats however, meaning that the biodiversity in these areas falls dramatically. The trees also stop soil run off into rivers, which it will do if there are none left.

78
Q

Define Conservation

A

The maintenance of biodiversity, including diversity between species, genetic diversity within species, and maintenance of a variety of habitats and ecosystems.

79
Q

How does an increase in human population threaten biodiversity?

A

Over exploitation of populations for food, sport, and commerce.

80
Q

How does an increase in human population threaten biodiversity?

A

Over exploitation of populations for food, sport, and commerce. This is a problem if the species cannot replenish itself faster than it is being killed.
Habitat disruption and fragmentation as a result of agriculture, pollution and buildings.
Species introduction to ecosystems by humans, which may out-compete the current species and disrupt the habitat.

81
Q

What economic advantages can helping conservation have?

A

Genetic diversity may be needed to breed different types of animal for food (disease resistant strains for example).
Maintaining biodiversity maintains the habitats where we originally got many of our medicines from today.
Natural predators of pests act as biological control agents which can help current farming methods.

82
Q

Define preservation

A

This is similar to conservation, however involves protecting sites which have not yet been disrupted by humans, and so ain to keep it that way.

Biology (8 decks)

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