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Biology > 19) Populations in Ecosystems > Flashcards

19) Populations in Ecosystems Flashcards

1
Q

Define ecology

A

The study of inter-relationships between organisms and their environment

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2
Q

Define community

A

All the populations of different species living in the same habitat

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3
Q

Define Habitat

A

The place where an organism lives, and there are many in an ecosystem

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4
Q

What is a microhabitat?

A

An area of smaller unit with its own microclimate

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5
Q

Define ecological niche

A

How an organism fits into an environment (where it lives and what it does), including biotic and abiotic conditions for survival and reproduction

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6
Q

What is the competitive exclusion principle?

A

That no 2 species occupy the same niche, so one species is completely removed if conditions remain the same (interspecific competition)

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7
Q

Define population

A

A group of individuals of one species that occupy a habitat at once

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8
Q

Define predator

A

An organism that feeds on another organism that is their prey

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9
Q

Define abundance

A

The number of individuals of a species in a given area

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10
Q

Define the term succession

A

The term used to describe changes over time in the species that occupy a particular area as populations fluctuate daily

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11
Q

Define conservation

A

Managing the Earth’s natural resources in a way that they can be made useful in the future

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12
Q

What is an ecosystem made up of?

A

A community and all the non-living factors of its environment

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13
Q

What are the 2 main processes in an ecosystem?

A

The flow of energy and the cycling of elements e.g. nutrients through/within the ecosystem

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14
Q

What is carrying capacity?

A

The size of population an ecosystem can support over a relatively long period of time

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15
Q

What is a predator-prey relationship?

A
  • type of interspecific relationship

- a significant reason for cyclic fluctuations

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16
Q

What are 3 causes of cyclic fluctuations?

A
  • predator-prey relationships
  • disease
  • climatic factors
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17
Q

Define predation

A

When one organism is consumed by another

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18
Q

What is selection pressure?

A

The individuals that are able to escape predators and withstand disease/adverse climate are more likely to survive and reproduce

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19
Q

What do populations of different species form?

A

Community

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20
Q

What are 2 reasons for population size to vary?

A
  • effect of abiotic factors

- intraspecific/interspecific competition

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21
Q

What are abiotic factors?

A

Non-living conditions which can influence where plants or animals live

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22
Q

What are biotic factors?

A

Living conditions which can influence where plants or animals live

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23
Q

Example of abiotic factors

A
  • water and humidity
  • light
  • temperature
  • pH
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24
Q

Example of biotic factors

A
  • competition

- predation

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25
Q

What may slow a population growth?

A

Limiting factors such as abiotic factors

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26
Q

When may you need to use a logarithmic scale on a growth curve?

A

When the curve is too steep and runs off the graph, for example when plotting bacteria growth, so you can see on the graph when the growth begins to slow

27
Q

How do you calculate percentage growth rate?

A

Population change
————————— x100
original population

28
Q

What is the competitive exclusion principle an example of?

A

Interspecific competition

29
Q

Who is intraspecific competition between?

A

Members of the same species

30
Q

Who is interspecific competition between?

A

Members of different species

31
Q

What are organisms competing for in interspecific competition?

A

Resources such as:

  • light
  • food
  • water
32
Q

What are organisms competing for in intraspecific competition?

A

Resources that determine population size:
- food
- water
- breeding sites
Greater availability = bigger population (vice versa)

33
Q

Describe the stages of primary succession (6 points)

A

1) pioneer species colonise a new land surfact as seeds and spores grow
2) abiotic conditions are harsh and only pioneer species are adapted to survive
3) pioneer species change abiotic conditions (die and decompose to form a basic soil)
4) conditions become less hostile so other species with different adaptations can move in and grow
5) some new species may change the environment so it is less suitable for the old species
6) a climax community forms

34
Q

How do pioneer species change the abiotic conditions?

A

They die and decompose to form a basic soil

35
Q

What is a climax community?

A

The last stage of succession, and is when a steady state is reached, so it won’t change much more

36
Q

What is the climax community in a polar climate and why?

A
  • Herbs or shrubs
  • not much available water
  • low temperatures
  • big changes between seasons
37
Q

What is the climax community in a temperate climate and why?

A
  • large trees
  • plenty of water
  • mild temperatures
  • not much change between the seasons
38
Q

How does secondary succession differ from primary succession? (3 points)

A

1) starts at a later stage so there is already a soil layer
2) doesn’t take as long to reach the climax community
3) pioneer species are larger e.g. shrubs

39
Q

What increases biodiversity during succession and why?

A
  • the ecosystem becoming more complex with a larger variety of species
  • larger number of habitats and niches
40
Q

What do more complex food webs lead to?

A

Increased biomass

41
Q

What happens at each stage of succession in general?

A

Better adapted plants and animals outcompete plants and animals that are already there and become the dominant species in the ecosystem

42
Q

How can conservation be managed?

A

By managing succession

43
Q

What are the 4 reasons for conservation?

A
  • personal
  • ethical
  • economical
  • cultural and aesthetic
44
Q

What are the personal reasons for managing conservation?

A

Maintain planet and life support system

45
Q

What are the ethical reasons for managing conservation?

A

Respect and co-exist with other species

46
Q

What are the economical reasons for managing conservation?

A

Maintain valuable genetic pools

47
Q

What are the cultural and aesthetic reasons for managing conservation?

A

Add variety, inspiration and interest into every day lives

48
Q

Why would you manage succession?

A

To prevent change to the next stage

49
Q

What happens if you remove the factor preventing further succession?

A

The ecosystem develops naturally into its climatic climax instead

50
Q

What 6 assumptions does the mark-release-recapture technique rely on?

A

1) proportion of marked:unmarked individuals in the sample is the same as in the whole population
2) the marked individuals re-distribute evenly among the community when released
3) the population has a definitive boundary
4) there are very few births and deaths (population size remains the same)
5) method of marking is not toxic and does not make the individual vulnerable
6) mark/label is not rubbed off or lost during investigation

51
Q

What are the 2 methods of measuring abundance of slow moving animals and plants?

A
  • frequency

- percentage cover

52
Q

What is frequency (measuring abundance)?

A
  • likelihood of a particular species occurring in a quadrat

- does not provide information on density or a detailed distribution of a species

53
Q

What is percentage cover (measuring abundance)?

A
  • estimate of area in quadrat covered by a particular species
  • useful for abundant/difficult to count species
  • rapid data collection
  • difficult if organisms occur in overlapping layers
54
Q

How can the abundance of mobile species be measured?

A

Mark-release-recapture method

55
Q

What is the mark-release-recapture method?

A

1) number of animals caught, marked and released back into the community
2) given number of animals is collected randomly and number of marked individuals in that sample is counted
3) work out the estimated population size

56
Q

What is the equation for estimated population size?

A

number of marked individuals that are recaptured

57
Q

What is an example of systematic sampling?

A

Belt transect

58
Q

What is an example of random sampling?

A

Quadrats

59
Q

What 3 things are important to consider when using quadrats?

A
  • size
  • position
  • number used
60
Q

When is using belt transects particularly useful?

A

Where there is succession

61
Q

What is an advantage of using a belt transect over a quadrat?

A

More informative

62
Q

What is an effect of predation on prey population?

A

They fall to low levels however rarely become extinct

63
Q

Why can predation not be reflected accurately in laboratories?

A

Populations can travel over a more diverse area in the wild

64
Q

What is the effect of predator-prey relationships on population size? (6 points)

A

1) prey population reduced
2) fewer prey means greater competition between predators for the remaining prey
3) predator population reduced as cannot catch enough prey to survive
4) fewer predators means fewer prey are eaten, so they can survive and reproduce
5) prey population increases
6) more prey means predator population also increases as there is more food

Biology (21 decks)

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