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A-Level Biology > Populations in Ecosystems > Flashcards

Populations in Ecosystems Flashcards

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1
Q

What is community?

A

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

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2
Q

What is an ecosystem?

A

All 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

What are biotic factors?

A

Living features of an ecosystem

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4
Q

What are abiotic factors?

A

Non-living features of an environment

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5
Q

What is an example of biotic factors?

A

Predators, disease

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6
Q

What is an example of abiotic factors?

A

Light, temperature

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7
Q

Give an example of how an organism has become adapted to abiotic factor

A

Otters have webbed paws so they can work on the land and swim

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8
Q

Give an example of how an organism has become adapted to biotic factor

A

Otters use rocks to smash open shellfish

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9
Q

What is a niche?

A

The role of a species within its habitat, consisting of both its biotic interactions

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10
Q

What is carrying capacity?

A

The maximum size of population an ecosystem can support without environmental degradation

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11
Q

What is intraspecific competition?

A

Competition between organisms of the same species

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12
Q

What is interspecific competition?

A

Competition between organisms of different species

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13
Q

What are the abiotic factors that affect population size?

A

Temperature
Light
pH
Water/humidity

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14
Q

How are quadrats used to estimate population size?

A

Placed on grid coordinates or at intervals along transect
Results reported as either a percentage cover or frequency
For slow moving/ non-mobile organisms

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15
Q

What should samples be?

A

Random and repeated to avoid bias

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16
Q

Describe the predator-prey relationship patterns

A

Prey eaten = predator population increases + prey decreases
Fewer prey = increased competition for food so predator population decreases
Fewer prey = prey population increases
Cycle begins again

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17
Q

What resources do organisms compete for?

A 
Food
Water
Shelter
Light
Mates (intraspecific only)
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18
Q

How is the mark-release-recapture used to estimate population size?

A 
Sample of species collected
Marked in harmless way
Released back into habitat
Wait a week then take 2nd sample from population
Count how many of 2nd sample are marked
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19
Q

What is the mark-release-recapture equation?

A

No. marked in 2nd sample

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20
Q

What happens if two species are competing for a resource?

A

The one better adapted to its surroundings will survive

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21
Q

What assumptions are made for the mark-release-recapture method?

A 
Marked individuals distributed evenly
No migration in or out of population
Few births or deaths
Method of marking does not affect survival
Mark does not come off
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22
Q

Why are ecosystems described as dynamic?

A

Populations constantly rise + fall
Any small change can have a small effect
Biotic + abiotic factors may alter conditions of ecosystem

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23
Q

Describe population growth

A

Population increases = resources plentiful
= more organisms competing for same amount of food/space
= resources limited = decline in population
= less competition for resources
= population grows

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24
Q

Describe the process of primary succession

A

Pioneer species colonies harsh conditions + area
Change abiotic factors of environment
The die and decomposed = adds nutrients to soil
This repeats = soil deep + nutritious
Allows more complex species to survive

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25
Q

What is a climax community?

A

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

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26
Q

How is a climax community reached?

A

Soil rich enough to support large trees or shrubs

Environment no longer changing

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27
Q

What is conservation?

A

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

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28
Q

Describe an example of pioneer species (bare rock to woodland)

A

Pioneer species (lichens) grow + break rock
Lichens die + decompose = soil thickens are decomposes more
Larger plants grow = soil deepens as they decompose
Shrubs+ small tress grow = out-compete grass
Diversity increases
Large trees become dominant species
Climax community

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29
Q

What is plagioclimax?

A

When succession is stopped artificially to stop a climax community from developing

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30
Q

How might succession be managed i order to aid conservation?

A

Sometimes succession needs to be prevented in order to observe an ecosystem
eg. stopping moorland from progressing into spruce forest = plagioclimax

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31
Q

What is sustainability?

A

Using enough resources to meet the needs of today’s society, without reducing the ability of people in the future to meet their own needs

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32
Q

What is the opinion of conservation?

A

Not everyone agrees with every conservation measure so often conflict between human needs and conservation
= careful management used to find a balance

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33
Q

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

A

Species might improve it to make it more suitable for other species
Species may worsen it by making it less suitable for other species

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34
Q

What ways are used to manage succession in the moorland ecosystem?

A

Animals allowed to graze = they eat growing points of shrubs = stops vegetation establishing + vegetation low
Managed fires are lit = secondary succession will occur = species grow back first (pioneer species) conserved
= large species will not grow back

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35
Q

What is a limiting factor?

A

Environmental conditions that limit the growth, abundance or distribution of an organism or population of organisms in an ecosystem

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36
Q

What is competitive exclusion principle?

A

Two species competing for the same limited resource, cannot coexist at constant population values as one will always out compete the other

37
Q

What are examples of conservation techniques?

A

National parks protect habitats = restrict urban development, industrial development + farming
Endangered species bred in captivity
Fishing quotas limit amount of certain fish species you can catch

38
Q

When is it best to use a log scale?

A

Rapid growth

Studying a long period of time

39
Q

Why would you use a log scale?

A

Reduces wide range quantities to tiny scopes

Clearer pattern shown

40
Q

What are factors that increase population growth?

A 
Health care
Infrastructure + resources
Economy
Food availability
Better quality of life
Industrial revolution
41
Q

What is the equation for population growth?

A

(Births + immigration) - (deaths + emigration)

42
Q

What is the equation for the percentage growth rate of population?

A

Population change during time period
——————————————————- X 100
Population at start of time period

43
Q

What are sampling methods?

A

Random

Systematic

44
Q

Why may a population fluctuate other then prey-predator relationship?

A

Disease

Climate change

45
Q

What are the two forms of active human conservation management?

A

Ex-situ

In-situ

46
Q

What is primary succession?

A

Where an area previously devoided of life s colonised by a community of organisms

47
Q

What is secondary succession?

A

Where land has been cleared of all plants but soil remains

48
Q

What is a habitat?

A

The place where an organism lives within an ecosystem

49
Q

What is a population?

A

Group of organisms of the same species occupying a particular space at a particular time that can potentially interbreed

50
Q

What are the characteristics of organisms present during early stage of succession

A 
Produce wind dispersed seeds
Survive in harsh conditions
Fast germination
Photosynthesise
Nitrogen-fixing
Produce asexually
51
Q

What is ex-situ?

A

Outside of natural habitats (eg. zoos)

52
Q

What in-situ?

A

Whole ecosystems and landscapes

53
Q

Why do populations not grow indefinitely?

A

Competition for space then reach carry capacity

54
Q

Why do species present during succession change?

A

Soil deepens as organisms grow, which allow for larger species to grow = increased competition

55
Q

What is a limitation of using the mark-release-recapture method?

A

Disturbance of habitat

56
Q

What is a species?

A

A group of organisms that can breed to produce fertile offspring

57
Q

Why are most characteristics distributed normally?

A

Result of polygenes (multiple genes each affected by the environment)

58
Q

What is a selection pressure?

A

Environmental pressure that is alternating the frequency of alleles in the population

59
Q

What is ecology?

A

The study of inter-relationships between organisms and their environment

60
Q

What is the biosphere?

A

The regions of the surface (land) and atmosphere (air) and Earth occupied by living organisms

61
Q

Describe a stable population - population pyramid

A

Birth + death rate are balanced
No change in population size
Typical of developed countries

62
Q

Describe increasing growth - population pyramid

A

High birth rate = wide base
Few old people = narrow apex
Typical of developed countries

63
Q

Describe decreasing growth - population pyramid

A

Low birth rate = narrow base
Low mortality rate = more elderly = wide apex
Applies to certain developed countries eg. Japan

64
Q

What is demographic transitions?

A

As countries develop economically, their human population display a patter of growth

65
Q

What are the four stages that demographic transitions are divided into?

A

Small and stable
Early expansion
Late expansion
Large and stable

66
Q

What do the stages depend on in demographic transition?

A

Death rate
Birth rate
Total population

67
Q

What are the adaptations of predators?

A

Fast
Camouflage
Sense of smell/sight

68
Q

What are the adaptions of prey?

A

Camouflage
Concealing behaviour
Speed
Protective features

69
Q

What is a stable community?

A

Where all species and environmental factors are in balance so that population size remains fairly constant

70
Q

Why is intraspecific population important?

A

Availability of resources determine population size
Greater availability = larger population size
More resources to grow + breed

71
Q

Why is it difficult to prove competition is factor affecting population size?

A

Many factors involved (abiotic)
Causal link has to be established
Lag time
Data on population size hard to obtain

72
Q

What are the difficulties of using quadrats?

A

Time consuming
May damage habitat
Element of personal bias
Difficult to identify + count every organism

73
Q

What are the advantages of point quadrats?

A

Smaller organisms
Smaller area
Specific detail

74
Q

What are the disadvantages of point quadrats?

A

Tedious
Hard to use
Time consuming

75
Q

When is systematic sampling important?

A

Gradual changes across habitat

Transitions within communities occur

76
Q

What are line transects?

A

Tape

Use quadrats

77
Q

What are belt transects?

A

Two tapes

Organisms recorded between two belts

78
Q

What are the advantages and disadvantages of line transects?

A 
Quick -A
Easily shows species - A
Clear visual of species change -A
Harder to see range across large area -D
Less data collected -D
79
Q

What are the advantages and disadvantages of belt transects?

A 
More data-A
Tell you more about abundance + range -A
Shows change clearly-A
Larger area -A
Time consuming -D
80
Q

What are the two methods to measure abundnace?

A

Frequency

Percentage cover

81
Q

What is the per quadrat equation?

A

No.of squares species occurs in
———————————————- X100
No.of squares in total

82
Q

What is the advantages and disadvantages of using frequency to measure abundance?

A

Useful where species easier to count -A
Quick idea of species present -A
No detailed info on distribution -D
Time consuming-D

83
Q

What is the advantages and disadvantages of using % cover to measure abundance?

A 
Useful when specie hard to count -A
Quick -A
Representation of density -A
Less precise -D
Subjective -D
84
Q

What are the disadvantages of the mark, recapture and release method?

A

Risk of predation changing sample size
Disturbance of habitat
Trauma or injury to organism

85
Q

What is preservation?

A

Maintaining individuals, populations and ecosystems in their current state without the exploitation of their natural resources

86
Q

What is species diversity?

A

The number of different species and numbers of individuals of each species within only one community

87
Q

What is genetic diversity?

A

The variety of genes possessed by the individuals that make up any one species

88
Q

What is ecosystem diversity?

A

The range of different habitats within a particular area

A-Level Biology (21 decks)

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