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biology > populations in ecosystems > Flashcards

populations in ecosystems Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

Define habitat

A

The place where an organism lives

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2
Q

Define population

A

All the organisms of one species in a habitat

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3
Q

Define community

A

Populations of different species in a habitat

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4
Q

Define ecosystem

A

A community, plus all the abiotic conditions in the area in which it lives

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5
Q

Define abiotic conditions

A

The non-living features of the ecosystem

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6
Q

Define biotic conditions

A

The living features of the ecosystem

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7
Q

Define niche

A

The role of a species within its habitat

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8
Q

Define adaptation

A

A feature that members of a species have that increases their chance of survival and reproduction

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9
Q

What does a niche include?

A
  • Biotic interactions e.g. the organism it eats or is eaten by
  • Abiotic interactions e.g. the oxygen an organism breathes in, and the carbon dioxide it breaths out
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10
Q

How many species are in a niche

A

One

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11
Q

What are niches separated by

A
  1. Time
  2. Location
  3. Behaviour
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12
Q

Why are niches important?

A

To avoid inter-species competition

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13
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
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14
Q

What are the 3 different types of adaptations?

A
  1. Physiological
  2. Behavioural
  3. Anatomical
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15
Q

Describe how adaptations become more common in the population

A
  • Organisms with better adaptations are more likely to survive, reproduce and pass on alleles for their adaptation
  • So the adaptation becomes more common in a population
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16
Q

Define population size

A

The total number of organisms of one species in a habitat

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17
Q

Define the carrying capacity

A

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

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18
Q

List abiotic factors which may affect population size

A
  1. Amount of light, water and space available
  2. Temperature
  3. Chemical composition of their surroundings
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19
Q

What resources might organisms compete for?

A
  1. Food
  2. Water
  3. Shelter
  4. Minerals
  5. Light
  6. Mates
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20
Q

Describe what happens to a population in their ideal abiotic conditions

A
  • Individuals grow and reproduce

- Population size increases

21
Q

Describe what happens to a population in their non-ideal abiotic conditions

A
  • Can’t grow fast and reproduce

- Population size decreases

22
Q

Define infraspecific competition

A

Infraspecific competition is when organisms of the same species compete with each other for the same resources

23
Q

Define interspecific competition

A

Interspecific competition is when organisms of different species compete with each other for the same resources

24
Q

What are the limiting factors for population size?

A

The amount of food available limits the population of any species

25
Q

Define predation

A

It is where an organism (the predator) kills and eats another organism (the prey)

26
Q

Describe and explain the relationship between the prey population and the predator population

A
  • As the prey population increases, there’s more food for predators so the predator population grows
  • As the predator population increases, more pray are eaten so the prey population begins o fall
  • So there’s less food for the predators, so their population decreases
27
Q

How should you pick out a sample to investigate a population?

A
  • Chose an area to sample, it should be random to avoid bias, e.g. random number generator for co-ordinates
  • Repeat the sampling method to take many samples to reduce the likelihood the results are due to chance
28
Q

How do you estimate the number of individuals in the whole area via a sample?

A

Mean of data collected in the sample x size of whole area

29
Q

Define non-motile

A

Organisms that don’t move

30
Q

What are the 2 ways of investigating non-motile organisms?

A
  1. Quadrats

2. Transects

31
Q

Define species frequency

A

How often a species is found or the number of individuals of each species is recorded in each quadrat

32
Q

How do you measure the percentage covered?

A

Measured by counting how much of the quadrat is covered by the species

33
Q

What do transects find out

A

Can find out how many species are distributed in an area

34
Q

Describe belt transects

A

Quadrats are placed next to each other along the transect to work out species frequency and percentage cover along the transect

35
Q

Describe interrupted belt transects

A

Quadrats are placed along lines at intervals to cover a long distance

36
Q

What does mark-release-recapture measure

A

Measures abundance of motile species

37
Q

Describe a method where you conduct a mark-release-recapture investigation

A
  1. Capture a sample of a motile species
  2. Mark them in a harmless way
  3. Release back into the habitat
  4. Wait a measured amount of time, and take 2nd sample from the same population
  5. Count how many of the 2nd samples are marked
38
Q

What is the equation for mark-release-recapture

A

(total number of individuals in first sample x total number of individuals in the second sample) / number of marked individuals recaptured

39
Q

How can you mark a species harmlessly during a mark-release-recapture investigation?

A
  1. Place a spot of paint on them

2. Remove a tuft of fur

40
Q

How do you estimate the total population size from your data from a mark-release-recapture investigation?

A

(number caught in 1st sample x number caught in 2nd sample) / number marked in 2nd sample

41
Q

What assumptions do you make when estimating the total population size from your data from a mark-release-recapture investigation?

A
  1. Marked sample has had enough time and opportunity to mix back into the population and be distributed evenly
  2. Marking hasn’t affected the organism’s chances of survival
  3. There are no changes to the population size due to: births, death and migration during the study
42
Q

Define succession

A

Succession is the process by which an ecosystem changes over time, the biotic and abiotic conditions change

43
Q

What is meant by primary succession?

A

Where an area previously devoid of life is colonised by a community of organisms, there is no soil or organic material to start with

44
Q

Summarise the process of primary succession

A
  • Abiotic conditions are hostile, pioneer species can survive harsh abiotic conditions because they are specially adapted to and colonise the area
  • They change abiotic factors of their environment, they die and microorganisms decompose the dead organic material to form soil
  • Conditions become less hostile, so new organisms with different adaptations can move in and grow
  • Over time this allows more complex organisms to survive
45
Q

What is climax community and how is it reached

A
  • The final stage of succession where the ecosystem is balanced and stable
  • When the soil is rich enough to support large trees or shrubs and the environment is no longer changing
46
Q

Define conservation

A

The protection and management of species and habitats, in order to maintain biodiversity

47
Q

How might succession be managed in order to aid conservation?

A

Succession needs to be prevented in order to preserve an ecosystem at a certain point

48
Q

List various methods of conservation

A
  1. Plants can be conserved using seedbanks which tore lots of seeds from different plant species, if the plant becomes extinct in the wild the stored seeds can be used to grow new ones
  2. Fishing quotas are limited to the number of certain fish species fishermen are allowed to catch, reducing the numbers of fish that are caught and killed
  3. Protected areas like national parks and nature reserves protect habitats by restricting urban development, industrial development and farming
  4. Endangered species can be bred in captivity to increase their numbers and then returned to the wild

biology (46 decks)

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