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Biology A-level > Population in ecosystems > Flashcards

Population in ecosystems Flashcards

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1
Q

Define species

A

Group of similar organisms that reproduce to produce fertile offspring

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2
Q

Define population

A

All of the individuals of a species in a specific place at the same time

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3
Q

Define community

A

All of the populations of different species in a particular place at the same time

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4
Q

Why can two species not occupy the same niche?

A

Competitive exclusion principle

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5
Q

What is the name given to the maximum size a population can become?

A

Carrying capacity

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6
Q

What is a limiting factor in terms of population?

A

A factor which would limit the growth of a population

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7
Q

Example of a limiting factor of a population

A

Nutrients
Mineral ions
Light
Temperature
Predators
Disease

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8
Q

What are abiotic limiting factors

A

Non-living factors

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9
Q

What are biotic limiting factors?

A

Living factors

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10
Q

Why might temperature limit a population?

A

Every organism has a optimum temperature. Too cold, enzymes work slowly, too hot enzymes denature

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11
Q

Why might light limit a population?

A

Ultimate energy source. Allows photosynthesis. More photosynthesis= more plants and therefore more organisms which follow in the food chain

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12
Q

Why is pH a limiting factor of population?

A

pH affects the activity of enzymes

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13
Q

Why might water and humidity limit a population?

A

Humidity affects transpiration. Few organisms survive when water is scarce

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14
Q

What are two types of competition?

A

Interspecific and intraspecific

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15
Q

Describe interspecific competition

A

When individuals of different species compete for resources

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16
Q

Describe intraspecific competition

A

Individuals of the same species compete for resources

17
Q

If there is intraspecific competition and the environment stays constant, what will happen?

A

Competitive exclusion. One organism will be better suited to the environment so its population will increase, its competitors will decrease until extinction

18
Q

What does the competitive exclusion principle mean for niches?

A

No two organisms occupy the same niche

19
Q

What is a predator?

A

An organism which hunts and feeds on other animals

20
Q

What is prey?

A

An animal which is hunted and eaten by a predator

21
Q

Why do changes in conditions and number of predators affect evolution|?

A

Create a selection pressure so those best suited survive.

22
Q

Two types of sampling

A

Random and systematic

23
Q

What is used to sample systematically?

A

Belt transect

24
Q

What are three factors too assess when using quadrats?

A
  • Size of quadrat
  • Number of quadrat
  • Position of quadrat
25
Q

What are the two methods of measuring abundance?

A

Frequency and percentage cover

26
Q

How do you carry out the mark-release recapture technique?

A

Capture animals, mark and release them and wait for distribution. Capture again over same time period.
Estimate population size by
number in same 1 X number in sample 2/ marked in sample 2

27
Q

What assumptions does the mark-release recapture technique have?

A
  • Mark does not affect survival chances
  • Mark doesn’t wear off
  • No births or deaths
  • No migration
  • Distribute themselves evenly
  • Ratio of marked to unmarked in sample 2 is equal to marked to unmarked in whole population
28
Q

What is succession?

A

How an ecosystem changes overtime. Each organism makes an environment less hostile and is then outcompeted by better species

29
Q

What is the first stage in succession?

A

Pioneer species settle (first)

30
Q

What characteristics does a pioneer species have?

A
  • Asexual
  • Vast number of wind dispersed seeds
  • Photosynthetic
  • Nitrogen fixing
  • Withstand extreme coonditions
31
Q

What are the two types of succession?

A

Primary and secondary

32
Q

What is the final stage of succession?

A

Climax community

33
Q

What is the climax community in the UK?

A

Deciduous oak woodland

34
Q

What changes occur through succession?

A

Increased biodiversity
More complex food webs
Increased biomass

35
Q

What is conservation?

A

Management of the earths resources by humans so they can be used in the future

36
Q

What conditions does conservation maintains?

A

Ecosystems and biodiversity

37
Q

Why does conservation take place?

A

Personal, ethical, economic, cultural and aesthetic

38
Q

How can managing succession aid habitats?

A

Preventing the successional change, habitats will not disappear and species will not be out competed.

Biology A-level (22 decks)

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