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Alevel Biology > populations in an ecosystem > Flashcards

populations in an ecosystem Flashcards

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1
Q

population

A

All the individuals of one species in the same area at the same time

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2
Q

habitat

A

The range of physical, biological and environmental factors in which a species can live

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3
Q

community

A

all the species in a particular area at a particular time

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4
Q

ecosystem

A

a community and the non-living components of an area
they can range from very small to very large in size

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5
Q

Niche

A

An organism’s role within an ecosystem
their position in the food web and their habitat

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6
Q

carrying capacity

A

The maximum population size an ecosystem can support

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7
Q

abiotic factors

A

Non-living conditions of an ecosystem

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8
Q

biotic factors

A

Impact and interactions between organisms

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9
Q

interspecific competition

A

Competition between members of different species

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10
Q

intraspecific competition

A

Competition between members of the same species

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11
Q

when would you use random sampling

A

when there is a uniform distribution of the plant species
to avoid bias

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12
Q

What must you do to ensure your samples are representative?

A

Take a large sample (at least 30)
randomly sample

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13
Q

when would you use a line transect

A

When sampling a non-uniform area
e.g. a rocky shore

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14
Q

Belt transect

A

one tape measure is placed through an ecosystem that is not uniform
the quadrat is placed at every position along a tape measure

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15
Q

interrupted belt transect

A

one tape measure is placed through an ecosystem that is not uniform
the quadrat is placed at set intervals along the tape measure

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16
Q

what are the 3 measurements you can take when counting plants in a quadrat?

A

density
percentage cover
frequency

17
Q

density measurement

A

when you count the individualspresent

18
Q

frequency measurement

A

count how many squares out of the 100 contain the species you are investigating

19
Q

what is succession?

A

the change in an ecological community over time

19
Q

percentage cover measurement

A

investigator estimates the percentage of the entire quadrat covered with the species that is being investigated
standardise by counting 1% for every small square that is at least half covered by the plant

20
Q

when would you use mark-release-recapture?

A

Estimate the population size of motile organisms

21
Q

what is secondary succession?

A

there is a disruption that causes plants to be destroyed succession starts again, but the soil is already formed

22
Q

pioneer species

A

The first species to colonise an area
e.g. lichen

22
Q

what is primary succession?

A

a succession with a pioneer species colonizing bare rock or sand
the first time the land is colonised

23
Q

climax community

A

The final stage in succession
the most stable stage

24
Q

Humus

A

a thin layer of soil that forms in early primary succession

25
Q

Conservation of habitats

A

Protecting habitats as a means to protect species
maintains habitats and food sources

26
Q

effects of stabilising selection

A

the middle trait has a selective advantage and continues to be the most frequent in the population
range decreases as the extreme traits are lost over time

26
Q

what is the main advantage of managing succession?

A

conserves a range of habitats and a range of food sources
enables a wider range of species to survive

26
Q

assumptions of mark-release-recapture

A

the marked individuals released distribute evenly after being released
no migration
no births or deaths

27
Q

effects of directional selection

A

one of the extreme traits has a selective advantage
occurs when there is a change in the environment
the modal trait changes

27
Q

effects of disruptive selection

A

alleles for the extreme traits and the middling trait allele becomes less frequent
leads to speciation

28
Q

How would you randomly sample

A

place two tape measures at right angles to create a gridded area
use a random number generator to get coordinates
place the quadrate at the coordinates and collect the data
repeat at least 30 time

28
Q

How would you sample using a line transect

A

Place a tape measure at a right angle to the road/river/shoreline
place quadrat every set distance meters (e.g. 5 metres)
collect the data in each quadrat
repeat placing the tape
measure in parallel 30 times

28
Q

describe the mark-release-recapture method of sampling

A

an initial sample of the population is captured
individuals are marked and released
allow them time to randomly disperse
a second sample is captured
the total number captured in the second sample and the number recaptured with the marking are recorded

29
Q

describe the changes you would see in a succession

A

abiotic factors become less hostile
biodiversity increases
becomes more stable

Alevel Biology (14 decks)

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