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A Level Bio > Chapter 19 - Populations In Ecosystems > Flashcards

Chapter 19 - Populations In Ecosystems Flashcards

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Biology 101 flashcards
1
Q

Ecosystem

A

A community of living and non living organisms interacting with each other and their physical environment in a defined area.

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2
Q

Biotic factor

A

A living component of an ecosystem

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3
Q

Abiotic factor

A

A non-living component of an ecosystem

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4
Q

Population

A

Group of organisms of the same species living in the same area at the same time that can interbreed to make fertile offspring

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5
Q

Community

A

All the populations of different species are in the same area at the same time

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6
Q

Habitat

A

Part of an ecosystem in which particular organisms live

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7
Q

Microhabitat

A

A smaller habitat with its own microclimate within a larger habitat

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8
Q

Niche

A

The role of an organism in its ecosystem, including its position in the food web and habitat, each species occupies its own niche governed by adaptation to abiotic and biotic conditions

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9
Q

Competitive exclusion

A

A principle stating that two species cannot occupy the same niche in the same environment simultaneously.

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10
Q

Abiotic factors that can affect the population size of species within ecosystems

A
  • Temperature
  • Light
    -pH
  • water availability
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11
Q

How does temperature affect ecosystems

A
  • affects enzyme activity and metabolic rates
  • at low temperature enzymes work more slowly and at high temp enzymes denature
  • in plants and ectotherms (cold blooded animals) their metabolic rate is dependent on temperature so extreme temperatures can reduce survival and reproductive success and population size
  • endotherms use more energy to maintain body temperature when temp is outside their optimal temp this can decrease reproduction success and population size
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12
Q

How does light affect ecosystems

A
  • the higher light intensity the faster the rate of photosynthesis, inputting more energy into ecosystems
  • this increases plant growth and higher reproduction rate which increases population size
  • this provides more food for animals increasing their population sizes as well
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13
Q

How does pH affect ecosystem

A
  • affects enzyme activity, and populations are larger when pH levels are optimal for an organism’s enzymes.
  • Deviations from the optimal pH can lead to smaller population sizes.
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14
Q

How does water availability affect ecosystems

A
  • Populations are generally smaller under conditions of low water availability, as only drought-resistant species can thrive.
  • Low humidity increases transpiration in plants and water evaporation from animals, leading to decreased population sizes due to water stress.
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15
Q

What is the carrying capacity

A

The maximum population size an ecosystem can support

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16
Q

How does biotic factors affect an ecosystem

A
  • interspecfic competition
  • intraspecfic competitions
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17
Q

What is interspecific competition

A

When members of different species are in competition for the same resource that is in limited supply

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18
Q

What is intraspecific competition

A

When members of the same species are in competition for resources and mate

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19
Q

Describe the pattern on a predator prey relationship graph

A
  • the size of the predator and prey population both fluctuate
  • the prey population will always peak at a higher point due to predators being further along the food chain so requires to eat lots of prey to gain enough energy from their food as energy is lost at each trophic level
  • there will always be a lag time between prey and predator populations
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20
Q

Explain the 4 phases of the population growth curve

A

1) Lag phase (period of slow growth) - birth rate exceeds death rate, so population starts grow
2) log phase (period of rapid growth) - population expands exponentially when there is no restrictions to growth
3) stable state - limiting factors stop further growth leading to a stable population size
4) decline state - death rates higher than birth rates

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21
Q

What happens when populations reach the carrying capacity

A
  • Birth and death rates tend to equalise.
  • Population growth slows down, and the population size stabilises
  • If environmental conditions degrade, the population size might decrease
22
Q

What is limiting factors in terms of populations

A

conditions that prevent populations from increasing further by restricting access to essential resources.

23
Q

Examples of limiting factors

A
  • Biotic factors, such as competition, predation, and disease.
  • Abiotic factors, including the availability of light, water, and space.
24
Q

What happens in the competitive exclusion principle

A
  • during interspecific competition, the species that uses these resources more efficiently will eventually outcompete the other.
  • The more efficiently adapted species uses the necessary resources, preventing other species from accessing them.
  • Over time, the less competitive species may reduce and eventually become locally extinct.
25
Q

What causes intraspecific compression to occur

A

During natural population fluctuations
1) When resources are plentiful, survival and reproduction increase, leading to a rise in population size.
2) Too many individuals increases competition, reduces available resources, and causes population decline.
3) A decrease in competition allows for greater access to resources, leading to population recovery, and the cycle starts again.

26
Q

Typical predators adaptations

A
  • Sudden bursts of speed
  • Stealth
  • Camouflage
  • Better prey detection, like forward-facing eyes with sharp visi
27
Q

Typical adaptations of prey

A

1) mimicry
2) protective features
3) camaflouge
4) better predators detection

28
Q

Two types of quadrat

A
  • Point quadrat - This is a frame with a horizontal bar, and pins are pushed through at set intervals to touch the ground. Each species the pin touches is recorded.
  • Frame quadrat - This is a square frame divided into a grid. The type and number of species within each section of the quadrat is recorded.
29
Q

How to calculate frequency

A

Number of times a species is found a quadrat/ number of total squares in a quadrat (x100)

30
Q

What is the percentage cover

A

An estimate of the area within a quadrat that a species covers

31
Q

What are transects

A

straight lines made across an ecological area of study

32
Q

What is systematic sampling

A
  • a non-random sampling method where different areas within a habitat are sampled at regular intervals to avoid bias.
  • allows us to study of how species distributions change across different areas within a habitat.
33
Q

Two types of transects

A
  • continuous belt transects
  • interrupted belt transects
34
Q

What is Continuous belt transects

A

When quadrats placed continuously along the transect line to study populations and detect any changes across an environmental gradient.

35
Q

What is interrupted belt transects

A

When quadrats placed at regular intervals along the line rather than continuously, which is faster but provides less precise data on population changes

36
Q

Assumption of mark release recapture technique

A
  • The marked individuals distribute evenly among the rest of the population.
  • The population remains constant with no significant immigration, emigration, births, or deaths.
  • The marks are non-toxic and don’t increase predation rates or change behaviour.
  • The marks are permanent and cannot be lost.
37
Q

How to calculate mark capture release

A

Total indv in first sample x total indv in second sample/ number of recaptured marked individuals

38
Q

How to use mark release recapture technique

A

1) Capture a sample of individuals from the target population in a defined area.
2) Mark or tag each captured individual in some way (e.g. paint dots on them).
3) Release the marked individuals back into the original habitat.
4) Allow time for marked individuals to mix evenly throughout the population.
5) Recapture another sample in the same area
6) Record numbers of marked and unmarked individuals.
7) Estimate total population size using the mark release recapture formula

39
Q

How to investigate effect of abiotic factors on distribution

A

1) Placing the transect line perpendicular to the area you are recording
2) Taking quadrat samples at regular intervals.
3) Recording the percentage cover of the target species.
4) Measuring the environmental variable (e.g. pH) at regular intervals.
5) Producing a graph of the data and analysing the relationship.

40
Q

What is succession

A

Succession is the process by which ecosystems change over time due to changes in the environment, causing the plant and animal species present to change

41
Q

Two mains forms of succession

A
  • Primary succession
  • Secondary succession
42
Q

Primary succession

A

occurs on newly formed or exposed land with no soil or organic material

43
Q

Secondary succession

A

occurs in areas where an existing community has been removed or destroyed , leaving the soil intact but with no plant or animal species

44
Q

Stages of primary succession

A

1) pioneer species colonise bare rock or sand and are adapted to survive in harsh abiotic conditions
2) the death and decomposition of pioneer species causes abiotic conditions to become less harsh and form a thin layer of soil, humus
3) mosses and smaller plants can now survive, increasing the depth and nutrient content of the soil
4) this causes abiotic conditions to become less harsh allowing larger plants to survive and change the environment further, eventually reaches the final stage is known as the climax community which is where the community is dominated by trees
5) each new species change the environment so it becomes less suitable for previous species, so existing species is out competed by new species colonising
6) this increases biodiversity

45
Q

Typical adaptions of pioneer species

A
  • Ability to reproduce asexually.
  • contains Seeds that are dispersed by wind.
  • Rapid germination.
  • The ability to photosynthesise.
  • (Nitrogen fixation to enrich soil)
  • Extreme condition tolerance
46
Q

What is Conservation

A

Conservation is the sustainable management of the Earth’s natural resources and ecosystems by humans in a way that allows for maximum future use.

47
Q

Key elements of conservation include

A
  • Management of resources to ensure future productivity and resource availability.
  • Intervention to protect natural habitats and species.
  • Preserving genetic diversity.
  • Rehabilitating and reclaiming damaged ecosystems.
48
Q

Reasons for conservation

A

Economic reasons:
- Ecosystems contain valuable genetic resources.
- Balanced ecosystems maximise productivity.
- Future discoveries and industries relying on biodiversity.
Cultural and aesthetic reasons:
- Wildlife and scenery enrich human lives.
- Inspiring art, music, culture, and recreation
Ethical reasons:
- Species have intrinsic rights to exist.
- Humans should enable the coexistence of species.
- Respecting nature is ethically preferable.

49
Q

What causes climax communities

A

Unmanaged succession can lead to a change in the ecosystem, where the final stages causes loss of earlier habitats and species often resulting in the development of a climax community.

50
Q

How can we use succession management to conserve threatened species and habitats they contain

A

by manipulating environmental conditions to inhibit progression to the next stage.
For example:

Burning vegetation
Grazing by livestock
Removing saplings
Mowing

A Level Bio (18 decks)

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