Bio Topic 5: What is an ecosystem?

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What is the biosphere?
The part of the earth and its atmosphere inhabited by living organisms.
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Define ecosystem.
a community of organisms that interact with themselves and their physical environment
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What is the difference between abiotic and biotic factors?
Abiotic factors are physical and chemical factors like climate and soil type while biotic factors are the living components of the ecosystem.
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What does a habitat provide?
A distinct set of conditions for organisms to live in.
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What is a population?
A group of interbreeding individuals of the same species in a given area.
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What determines which species occur in a habitat?
Unless deliberately put there and maintained by humans, particular species lives in a certain habitat b/c it's adapted to it and able to survive and reproduce there.
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Outline solar energy output as an abiotic factor.
Light vital to plants for photosynthesis, has role in seed germination and affects behaviour in many animals. Affected by latitude, season, cloud cover + change in earth's orbit
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What affects the abiotic factor of climate?
rainfall, wind exposure and temperature.
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What is topography?
The shape and features of the earth's surface, includes altitude (affects the climate),slope, aspect (which direction land faces, and drainage.
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What are edaphic factors?
connected with the soil and include soil pH , mineral ion concentration and soil texture. Can have significant effect on plant distribution.
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Why is soil texture important?
Sandy soils are well drained and rarely get waterlogged, but can dry out in drought. Clay gets easily waterlogged but retains water well.
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What is a catastrophe in terms of abiotic factors?
infrequent events that considerably disturb conditions. Include earthquakes, hurricanes, floods, volcanic eruptions and fires.
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Name and outline 3 biotic factors
Competition for resources like food, light, water and space (inter & infraspecific). Relationships between organisms including grazing, predation, disease, parasitism and mutualism.
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Why are biotic factors density dependent?
B/c the effects are directly related to the size of the population relative to the available area. Larger the pop. density, greater the competition for resources.
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What are anthropogenic factors? Give some examples.
those arising from human activity, can be either biotic or abiotic. Includes deforestation, grazing, increase in CO2 emissions and climate change.
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How are polar bears adapted to their habitat?
They have thick firm hairs providing insulation, long oily outer hairs to easily shed water but inner hairs are fine to provide insulation by trapping air.
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How are rabbits adapted to their diet?
They eat their faeces as grass s hard to digest so to gain max nutrition from food have to eat it twice.
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What is succession?
process in which plant and animal communities are replaced in a given area over time by a series of different & usually more complex communities.
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When/where does primary succession occur?
starts in newly formed habitat when there's never been a community before e.g. bare rocks or open waters
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What are the first organisms to colonise during primary succession? What is the term for these first organisms?
Lichen and algae, they're called pioneer species
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Why are lichen and algae able to colonise the bare rock?
Because they're the only organisms that can cope w. extremes of temp and lack of water , soil and nutrients
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What do the pioneer species do to the bare rock?
They start to break the rock surface allowing the beginnings of soil. They change the conditions just enough to make them suitable for other species like wind-blown mosses.
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How do the mosses then change the soil?
They build up more organic matter in the soil allowing it to hold water. This then allows small seeds with shallow roots that have reached the habitat to grow.
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What is a climax community?
A relatively stable community, usually dominated by trees.
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What determines the nature of the climax community?
Depends on the environmental conditions present eg. climate, soil conditions, species present
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What is the dominant species?
The organism exerting an overriding influence over the plants, animals and microbes of the community. Usually the largest or most abundant in the plant community
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Why does a climax community sometimes have less biodiversity than previous stages of succession?
Because the dominant species outcompetes others.
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Give a real-life example of a climax community without trees.
The Keen of Hamar in Shetland: a large area of bare, stony hill.
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What stage of succession does this community look like?
A pioneer community as still has bare rocks w. no grass/mosses growing
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Why is Keen of Hamar without trees?
One possibility is the sandy soil can't hold water so shows drought conditions just a few days after it's rained.
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Why does the Keen of Hamar need to remain a pioneer-type habitat?
The species inhabiting the community are slow-growing and couldn't successfully compete what more vigorously growing grasses
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What is secondary succession?
Secondary succession occurs on bare soil where an existing community had been cleared.
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Give 2 examples of secondary succession.
Plants beginning to grow on a ploughed field or plants starting to grow after a forest fire.
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What adaptations doe Groundsel (a pioneer species) have that allows it to take advantage of newly bare soil with little/no competition?
Its seeds are widely dispersed by wind, it grows rapidly and has a short life cycle and also has abundant seed production.
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What is deflected succession?
When a community only stays stable b/c human activity prevents succession from running its course
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How do sheep create deflected succession in parts of the UK?
Sheep grazing prevents many grasslands developing into woodlands.
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Dredging a pond/lake also causes deflected succession. How does succession turn open water to a terrestrial woodland?
Sediment deposits decrease the water depth creating swamp and marshland and eventually woodland as conditions dry out.
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What techniques do humans use to deflect succession?
Grazing, mowing or burning can be used.
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Other cards in this set

Card 2

Front

Define ecosystem.

Back

a community of organisms that interact with themselves and their physical environment

Card 3

Front

What is the difference between abiotic and biotic factors?

Back

Preview of the front of card 3

Card 4

Front

What does a habitat provide?

Back

Preview of the front of card 4

Card 5

Front

What is a population?

Back

Preview of the front of card 5
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