7.4 Populations in ecosystems Flashcards

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1
Q

Define community

A

All the different species that live in one area and interact with each other

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2
Q

Define ecosystem

A

All the living organisms found in one area, combined with non-living aspects of their environment. Can vary from very large to very small

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3
Q

Describe biotic factors, giving examples

A

Biotic = living features of an ecosystem, e.g. predators, disease

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4
Q

Describe abiotic factors, giving factors

A

Abiotic = non-living features of an ecosystem, e.g. light, temperature

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5
Q

Define habitat

A

The place where an organism lives within an ecosystem

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6
Q

Define a niche

A

The role of a species within its habitat, consisting of both its biotic interactions
e.g. what it eats, and abiotic interactions, e.g. time of day its active

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7
Q

What is meant by carrying capacity?

A

The maximum size of population an ecosystem can support

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8
Q

Name four abiotic factors that affect population growth

A
  • Temperature
  • Light
  • pH
  • Water
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9
Q

What is meant by intraspecific competition

A

Competition between organisms of the same species

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10
Q

What is meant by interspecific competition?

A

Competition between organisms of different species

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11
Q

What resources might organisms compete for?

A

Food, water, shelter, minerals, light, mates (intraspecifc only)

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12
Q

Describe the pattern of a typical predator-prey relationship in terms of population change

A
  • Prey is eaten by predator, resulting in predator population increasing and prey population decreasing
  • Fewer prey means increased competition for food, so predator populations decreases
  • Fewer predators means more prey survives, and the cycle begins again
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13
Q

How are quadrats used for estimating population size?

A

Can be placed on grid coordinates, or at intervals along a belt transect. Results reported as either percentage cover or frequency. For slow-moving or non-motile organisms

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14
Q

How is mark-release-recapture used for estimating population size?

A
  • A sample of a species is captured, marked, then released back into the same area they were caught
  • After a certain period of time another sample is captured, and the number of marked organisms are counted
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15
Q

What is the equation for mark-release-recapture?

A

Estimated population size = total no. of individuals in 1st sample x total no. of individuals in 2nd sample / no. of marked individuals recaptured

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16
Q

What assumptions does the mark-release-recapture method make?

A
  • Marked individuals distribute evenly
  • No migration in or out of the population
  • Few births or deaths
  • Method of marking does not affect survival
  • Mark does not come off
17
Q

Why are ecosystems described as being dynamic?

A
  • Populations constantly rise and fall
  • Any small change can have a large effect
  • Biotic and abiotic factors may alter the conditions of the ecosystem
18
Q

What is meant by primary succession?

A

Where an area previously devoid of life is colonised by a community of organisms

19
Q

Summarise the process of primary succession

A
  • Pioneer species can survive harsh conditions and colonise the area
  • They change abiotic factors of their environment
  • Over time, this allows more complex organisms to survive
20
Q

What is the climax community?

A

The final stage of succession, where the ecosystem is balanced and stable

21
Q

How is the climax community reached?

A

It is reached when the soil is rich enough to support large trees or shrubs, and the environment is no longer changing

22
Q

How might a species alter the environment that develops during succession?

A

A species may improve the environment to make it more suitable for other species.
Alternatively, a species may worsen the environment by making it less suitable for other species

23
Q

Define conservation

A

The protection and management of species and habitats, in order to maintain biodiversity. Methods need to be adapted to the ecosystem in question

24
Q

How might succession be managed in order to aid conservation?

A

Sometimes succession needs to be prevented in order to preserve an ecosystem at a certain point, e.g. stopping moorland from progressing into spruce forest, this is called a plagioclimax