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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

What is ecology

A

The study of inter relationships between organisms and their environment

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2
Q

Name the abiotic factors of an ecosystem

A

Light
Temp
Soil PH
water availability

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3
Q

How does light affect an ecosystem

A

Affects rate of Photosynthesis and so plant growth and so food availability as biomass is affected

More energy available for spore and seed formation with more light

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4
Q

How does temperature affect an ecosystem

A

Affects rate of Respiration and Photosynthesis due to enzymes.

Affects water availability

Affects body temp so energy used to regulate temp not growth and reproduction

Cold blooded= enzymes denature

Warm blooded= less energy for reproduction so mature slower

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5
Q

What biotic factors are there in an ecosystem

A

Food availability
Predation
Disease
Competition

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6
Q

How do predators affect an ecosystem

A

Kill organisms so reduce population

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7
Q

How does food availability affect an ecosystem

A

Competition

Starvation

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8
Q

How does competition affect an ecosystem

A

Some will starve and die reducing population

Not enough supply to support all

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9
Q

How does disease affect an ecosystem

A

Makes more succeptible to predation so may fall prey

May die from disease

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10
Q

Define population

A

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

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11
Q

Define ecosystem

A

Habitat and the community of organisms within it

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12
Q

Define community

A

All populations of different species living at the same place at the same time

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13
Q

Define habitat

A

Place where an organism normally lives

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14
Q

Define ecological niche

A

Where an organisms lives and what it does

the biotic and abiotic factors its adapted to

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15
Q

Define the competitive exclusion principle

A

No two species can occupy the same ecological niche because they will outcompete one another

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16
Q

Define carrying capacity

A

The maximum size of the population able to be supported by an ecosystem

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17
Q

Describe the growth curve

A

Slowth then rapid and then fluctuations

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18
Q

Why is a logarithmic scale used

A

To clearly show the rate of growth

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19
Q

How does PH affect a population

A

Alter enzyme activity

Decreased Respiration and Photosynthesis so reduced carrying capacity

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20
Q

How does water and humidity affect a population

A

More humid = lower WP gradient= reduced transpiration and water loss

Less water = only adapted organisms survive

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21
Q

What are the two types of competition

A

Intra and inter

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22
Q

What does intraspecific competition occur for

A

Light water mates

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23
Q

What does interspecific competition occur for

A

Habitat light water food

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24
Q

How are predators adapted

A

Camouflage
Faster movement
Better sense to detect prey

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25
Q

How are prey adapted

A

Camouflage
Concealment behaviour
Spines (protective features)

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26
Q

Why might lab results be different in terms of predator prey relationships

A

Prey will go extinct as no other source of food or refuges

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27
Q

What is a selection pressure

A

A factor that drives selection

28
Q

Define succession

A

Gradual changes in community over time

29
Q

Describe the process of succession

A

New species arrives changing the conditions making them less hostile, making them less suitable for the previous species and more suitable for other species which outcompete it.

30
Q

What happens to biodiversity during succession

A

Increases and then decreases at climax community

31
Q

Define pioneer species

A

First species to colonise

32
Q

How are pioneer species adapted

A

Asexual reproduction (single organism can establish whole pop)

Produce many wind dispersed seeds

Rapidly germinating seeds

Able to Photosynthesise (no other animals available)

Fix nitrogen from air

Tolerate extreme conditions

33
Q

Define climax community

A

Stable community where no further succession occurs

34
Q

What are the features of succession

A 
Abiotic factors become less hostile
Greater no and variety of habitats
Greater biodiversity
More complex food webs
Greater biomass
35
Q

Describe primary succession

A

Bare rock is colonated by lichens

Weathering of rock and decomposition of dead lichen =soil and nutrients

Nutritious soil can support a variety of life

Biodiversity increases so environment is less hostile

Thicker soil builds

Flowers and ferns establish

Climax community reached so species in equilibrium and biodiversity decreases

36
Q

What is the difference between primary and secondary succession

A

Secondary begins with a devastated ecosystem where soil is available and succession is more rapid

37
Q

How does DOM change with succession

A

Increases as more organisms are present which then die

38
Q

How does humidity change with succession

A

Increases as more plants means more transpiration and less air flow

39
Q

How does PH change with succession

A

Decreases as DOM is broken down into fatty acids and carboxylic acids

40
Q

How does transpiration/evaporation change with succession

A

Decreases as more plants are present and so humidity decreases, decreasing the WP gradient

41
Q

How does NaCl conc change with succession

A

Decreases as less sea spray hits the soil

42
Q

How does soil temp change with succession

A

Increases as more plants means more Respiration so more energy released

More decomposition so more DOM so less drainage and more water

43
Q

How does wind speed change with succession

A

Decreases as more plants act as wind break

44
Q

Define conservation

A

Management of earth’s natural resources to. Maximise use in the future

45
Q

Reasons for conservation

A

Personal (life support system)
Ethical (species should be able to coexist)
Economic (many genes able to produce many valuable substances)
Cultural and aesthetics (inspiration for books and songs)

46
Q

Why might we want to manage succession

A

So that rare species don’t go extinct due to being outcompeted

47
Q

How might succession be managed

A

Grazing of sheep

Burning

48
Q

What organisms are quadrats used for

A

Non-motile organisms

49
Q

Describe the types of quadrat

A

Frame
Count organisms in squares

Point
Count organisms touching poles

50
Q

What factors need to be taken into account when using quadrats

A

Size (large quadrats for large organisms)

No of samples (large is more reliable but more time consuming)

Position (random sampling to avoid bias)

51
Q

What is a running mean and why is it used

A

Mean calculate everytime a new sample is taken

When mean is constant the number of samples is representative

52
Q

Describe random sampling using quadrats

A 
Set out grid
Randomly choose coordinates
Place quadrat at coordinates
Count organisms in quadrat
Repeat 10 times and calculate Mean
53
Q

Define systematic sampling and an example

A

Collecting data at regular intervals

Belt transect

54
Q

What’s the difference between a line and belt transect

A

With a line transect quadrats are placed at regular intervals

With belt transects the quadrats are placed every length of the quadrat

55
Q

What are the advantages of belt transect over line transects

A

More accurate

Less bias

56
Q

What are the disadvantages of belt compared to line transects

A

More damaging

More time consuming

57
Q

Define abundance

A

Number of individuals of a species in an area

58
Q

What are the ways to measure abundance

A

Percentage cover
Frequency
Population density

59
Q

Describe how frequency is calculated

A

Expressed as a percentage or as a X out of y.

60
Q

How is population density calculated

A

Number of individuals per area

61
Q

What are the advantages and disadvantages of using percentage cover

A

Ad:
Good when organisms are difficult to count
Less time consuming

Dis:
Organisms may overlap making % over 100

62
Q

What are the advantages and disadvantages of Using frequency

A

Ad:
Quick and easy

Dis:
No information on density or distribution

63
Q

When is Mark release recapture used

A

On motile organisms

64
Q

What assumptions are made in MRR

A

Markings don’t rub off

Sample is proportional to population

Organisms have enough time to mix

Marking is non toxic and doesn’t make them more likely to be prey

No births or deaths

No immigration or emigration

65
Q

Outline method of MRR

A 
Capture organisms
Mark all
Release and leave for 24 hrs
Capture and ratio of marked to total captures
Use ratio to calculate whole population

biology (28 decks)

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