Ecosystems, Populations And Sustainability Flashcards

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1
Q

Define ecosystems

A

All the living organisms found in one area and the non living aspects of their environment
Can range in size from rock pool to African savannah
Known as ‘dynamic’ as they depend on interactions between biotic and abiotic factors

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2
Q

Describe biotic factors with examples

A

The living features of an ecosystem
Any from
Predators
Disease
Symbiosis
Parasitism
Mutualism
Competition

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3
Q

Describe abiotic factors and give examples

A

Non living features of an ecosystem
Any from
Light
Soil
Water availability
Water movement
Oxygen concentration
pH
Wind
Salinity
Temperature
Humidity

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4
Q

What is biomass and how is it transferred?

A

Total weight of living matter in a certain area, transferred up trophic levels through consumption. Can be measured in terms of mass of carbon or dry mass of tissue

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5
Q

Give the formula for the efficiency for a biomass transfer

A

Efficiency = ( Biomass transferred / Biomass intake ) x100

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6
Q

How can human activities affect biomass transfer

A

• Light, water, temperature maximised
• Increased nutrients in soil
• Pests and weeds removed
• Growth rates boosted through steroids, selective breeding etc

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7
Q

Outline the role of microorganisms in the nitrogen cycle

A

Nitrogen-fixing bacteria e.g. Rhizobium in roots and Azotobacter in soil convert gaseous nitrogen into ammonia
Nitrifying bacteria e.g. Nitrosomonas convert ammonium compounds into nitrites
Nitrobacter then converts nitrites to nitrates

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8
Q

Outline the role of organisms in the carbon cycle

A
  • Respiration of plants and animals add carbon dioxide into the atmosphere
  • Photosynthesis of plants removes carbon dioxide from the atmosphere
  • Decomposers (microorganisms) decay plant and animal material into carbon dioxide
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9
Q

What is meant by primary succession

A

Where an area previously devoid of life is colonised by a community of organisms

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10
Q

Summarise the process of primary succession

A
  • Pioneer species, able to survive harsh conditions, colonise the area
  • They die, decompose and add nutrients to the ground
  • Over time, this allows more complex organisms to milestone
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11
Q

What is the climax community and how is it reached?

A

The final stage of succession, where the ecosystem is balanced and stable. It is reached when the soil is rich enough to support large trees or shrubs, and the environment is no longer changing

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12
Q

What is deflected succession

A

Where succession is interrupted, usually by human interference

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13
Q

What is sampling

A

Selecting a group of individuals that will represent the whole target population
Allows us to measure the distribution and abundance of organisms

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14
Q

Give methods of sampling and explain how they are used

A

Quadrats = used in small areas. Randomly or regularly placed across habitat. Frequency or % cover calculated
Transects = used in larger areas. Sample taken along a line that crosses the habitat. Can be combined with quadrats in the form of a belt transect

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15
Q

Define carrying capacity

A

The maximum population size that a habitat can support, defined by the presence of limiting factors

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16
Q

Give factors that limit the maximum size of a population

A

Food
Water
Light
Oxygen
Nesting sites
Shelter
Parasites
Predators

17
Q

Describe the pattern of a typical predator-prey relationship in terms of population change

A

Prey is eaten by predator, resulting in predator population increasing and prey population decreasing
Fewer prey means greater competition for food, so predator population decreases
Fewer predators means more prey survives, and the cycle begins again

18
Q

What is meant by intraspecific and interspecific competition

A

Intraspecific= competition between organisms of the same species
Interspecific= competition between organisms of different species

19
Q

Differentiate between conservation and preservation

A

Conservation= maintains biodiversity of a habitat by allowing the sustainable use of the resources there
Preservation= maintains biodiversity of a habitat by minimising human impact

20
Q

Give reasons why we conserve and preserve habitats

A

Economic= Food source, natural pest control, boosts tourism
Social= many organisms can be used in medicine, aesthetics
Ethical= we have a responsibility to maintain habitats for future generations

21
Q

Define sustainability

A

Using resources in a way that also maintains them for future generations

22
Q

What methods allow sustainable use of an ecosystems resources

A

Timber production= coppicing to encourage growth, replacing felled trees, selective cutting
Fishing= stocks not depleted, no overfishing, can continue indefinitely

23
Q

Give an example of how the conflict between conservation and human needs can be balanced

A

Terai region (Nepal). Over-exploited for use in fuel. Locals now have a responsibility to look after the forest. ‘Corridors’ placed to enable migration

24
Q

Give an example of how human effects are controlled in sensitive ecosystems

A

Galapagos islands. Many species endangered due to hunting and tourism. New species introduced, but caused damage to native species. Trying to find a balance