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A-Level Biology > Populations in Ecosystems > Flashcards

Populations in Ecosystems Flashcards

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
What is a climax community?
The final stage of succession, where the ecosystem is balanced and stable
26
How is a climax community reached?
Soil rich enough to support large trees or shrubs | Environment no longer changing
27
What is conservation?
The protection and management of species and habitats, in order to maintain biodiversity
28
Describe an example of pioneer species (bare rock to woodland)
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
29
What is plagioclimax?
When succession is stopped artificially to stop a climax community from developing
30
How might succession be managed i order to aid conservation?
Sometimes succession needs to be prevented in order to observe an ecosystem eg. stopping moorland from progressing into spruce forest = plagioclimax
31
What is sustainability?
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
32
What is the opinion of conservation?
Not everyone agrees with every conservation measure so often conflict between human needs and conservation = careful management used to find a balance
33
How a species might alter the environment that develops during succession?
Species might improve it to make it more suitable for other species Species may worsen it by making it less suitable for other species
34
What ways are used to manage succession in the moorland ecosystem?
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
35
What is a limiting factor?
Environmental conditions that limit the growth, abundance or distribution of an organism or population of organisms in an ecosystem
36
What is competitive exclusion principle?
Two species competing for the same limited resource, cannot coexist at constant population values as one will always out compete the other
37
What are examples of conservation techniques?
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
When is it best to use a log scale?
Rapid growth | Studying a long period of time
39
Why would you use a log scale?
Reduces wide range quantities to tiny scopes | Clearer pattern shown
40
What are factors that increase population growth?
``` Health care Infrastructure + resources Economy Food availability Better quality of life Industrial revolution ```
41
What is the equation for population growth?
(Births + immigration) - (deaths + emigration)
42
What is the equation for the percentage growth rate of population?
Population change during time period ------------------------------------------------------- X 100 Population at start of time period
43
What are sampling methods?
Random | Systematic
44
Why may a population fluctuate other then prey-predator relationship?
Disease | Climate change
45
What are the two forms of active human conservation management?
Ex-situ | In-situ
46
What is primary succession?
Where an area previously devoided of life s colonised by a community of organisms
47
What is secondary succession?
Where land has been cleared of all plants but soil remains
48
What is a habitat?
The place where an organism lives within an ecosystem
49
What is a population?
Group of organisms of the same species occupying a particular space at a particular time that can potentially interbreed
50
What are the characteristics of organisms present during early stage of succession
``` Produce wind dispersed seeds Survive in harsh conditions Fast germination Photosynthesise Nitrogen-fixing Produce asexually ```
51
What is ex-situ?
Outside of natural habitats (eg. zoos)
52
What in-situ?
Whole ecosystems and landscapes
53
Why do populations not grow indefinitely?
Competition for space then reach carry capacity
54
Why do species present during succession change?
Soil deepens as organisms grow, which allow for larger species to grow = increased competition
55
What is a limitation of using the mark-release-recapture method?
Disturbance of habitat
56
What is a species?
A group of organisms that can breed to produce fertile offspring
57
Why are most characteristics distributed normally?
Result of polygenes (multiple genes each affected by the environment)
58
What is a selection pressure?
Environmental pressure that is alternating the frequency of alleles in the population
59
What is ecology?
The study of inter-relationships between organisms and their environment
60
What is the biosphere?
The regions of the surface (land) and atmosphere (air) and Earth occupied by living organisms
61
Describe a stable population - population pyramid
Birth + death rate are balanced No change in population size Typical of developed countries
62
Describe increasing growth - population pyramid
High birth rate = wide base Few old people = narrow apex Typical of developed countries
63
Describe decreasing growth - population pyramid
Low birth rate = narrow base Low mortality rate = more elderly = wide apex Applies to certain developed countries eg. Japan
64
What is demographic transitions?
As countries develop economically, their human population display a patter of growth
65
What are the four stages that demographic transitions are divided into?
Small and stable Early expansion Late expansion Large and stable
66
What do the stages depend on in demographic transition?
Death rate Birth rate Total population
67
What are the adaptations of predators?
Fast Camouflage Sense of smell/sight
68
What are the adaptions of prey?
Camouflage Concealing behaviour Speed Protective features
69
What is a stable community?
Where all species and environmental factors are in balance so that population size remains fairly constant
70
Why is intraspecific population important?
Availability of resources determine population size Greater availability = larger population size More resources to grow + breed
71
Why is it difficult to prove competition is factor affecting population size?
Many factors involved (abiotic) Causal link has to be established Lag time Data on population size hard to obtain
72
What are the difficulties of using quadrats?
Time consuming May damage habitat Element of personal bias Difficult to identify + count every organism
73
What are the advantages of point quadrats?
Smaller organisms Smaller area Specific detail
74
What are the disadvantages of point quadrats?
Tedious Hard to use Time consuming
75
When is systematic sampling important?
Gradual changes across habitat | Transitions within communities occur
76
What are line transects?
Tape | Use quadrats
77
What are belt transects?
Two tapes | Organisms recorded between two belts
78
What are the advantages and disadvantages of line transects?
``` 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
What are the advantages and disadvantages of belt transects?
``` More data-A Tell you more about abundance + range -A Shows change clearly-A Larger area -A Time consuming -D ```
80
What are the two methods to measure abundnace?
Frequency | Percentage cover
81
What is the per quadrat equation?
No.of squares species occurs in ---------------------------------------------- X100 No.of squares in total
82
What is the advantages and disadvantages of using frequency to measure abundance?
Useful where species easier to count -A Quick idea of species present -A No detailed info on distribution -D Time consuming-D
83
What is the advantages and disadvantages of using % cover to measure abundance?
``` Useful when specie hard to count -A Quick -A Representation of density -A Less precise -D Subjective -D ```
84
What are the disadvantages of the mark, recapture and release method?
Risk of predation changing sample size Disturbance of habitat Trauma or injury to organism
85
What is preservation?
Maintaining individuals, populations and ecosystems in their current state without the exploitation of their natural resources
86
What is species diversity?
The number of different species and numbers of individuals of each species within only one community
87
What is genetic diversity?
The variety of genes possessed by the individuals that make up any one species
88
What is ecosystem diversity?
The range of different habitats within a particular area

A-Level Biology (21 decks)

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