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Biology Paper 2 > Populations & Sustainability > Flashcards

Populations & Sustainability Flashcards

1
Q

Describe and explain the phases of a population growth curve

A

Slow growth (lag)
- Small numbers of individuals initially present
- Reproduction increases total population
- Birth rate > death rate

Rapid growth (log)
- Number of breeding individuals increase
- Total population multiplies exponentially
- No limiting factors present
- Birth rate > death rate

Stable state (stationary)
- Limiting factors prevent further population growth
- Population fluctuates
- Overall size stays relatively stable
- Birth rate ≈ death rate

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2
Q

Define carrying capacity

A

Maximum population size an environment can support

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3
Q

Give examples of abiotic factors that limit population size

A
  • Temperature
  • Light
  • Water or oxygen availability
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4
Q

Give examples of biotic factors that limit population size

A
  • Predators
  • Disease
  • Competition
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5
Q

Define immigration

A
  • Movement of individual organisms into a particular area
  • Causes population to increase
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6
Q

Define emigration

A
  • Movement of individual organisms away from a particular area
  • Causes population to decrease
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7
Q

State the factors that would cause an increase in population size

A
  • Increase in quantity or quality of food supply
  • Availability of clean water
  • Lack of predators
  • Favourable environmental conditions
  • Availability of light
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8
Q

Define density independent factor

A
  • Factor that has effect on population regardless of its size
  • e.g. fire, volcano, storm
  • Can remove entire species from an area
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9
Q

Define density dependent factor

A
  • Effect of factor dependent on population size
  • e.g. more predators in area = more prey killed
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10
Q

Define interspecific competition

A

Competition between different species

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11
Q

Define intraspecific competition

A

Competition between members of same species

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12
Q

When does competition arise?

A
  • When resources are not present in adequate amounts
  • To satisfy needs of all individuals who depend on them
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13
Q

Describe what happens to birth and death rates as competition increases

A
  • Rate of reproduction decreases
  • Fewer organisms have enough resources to reproduce
  • Death rate increases
  • Fewer organisms have enough resources to survive
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14
Q

Outline the possible effects of interspecific competition

A
  • Species seeking to occupy similar niche
  • Reduction in resources available to competing populations
  • If species are equally adapted:
  • Reproduction rate decreases in all species
  • Population sizes decrease
  • If one species better adapted:
  • Less well adapted species outcompeted
  • Numbers decline
  • Potentially to extinction
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15
Q

Define competitive exclusion principle

A
  • Two species compete for same resource
  • One that uses resource more effectively will eliminate the other
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16
Q

Describe the cycle of population size changes that occur following intraspecific competition

A
  • Initially resources plentiful
  • Population increases
  • Birth rate > death rate
  • Resources become limited as more organisms compete for resource
  • Population decreases
  • Birth rate < death rate
  • Reduced population results in less competition so more organisms survive and reproduce
  • Population increases
  • Birth rate > death rate
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17
Q

Define predation

A

When predator kills and eats prey

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18
Q

What type of competition is predation?

A

Interspecific

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19
Q

Describe and explain the predator-prey cycle

A

1 - Increase in prey population - More food for predators - More predators survive and
reproduce - Predator population increases

2 - Increased predator population
eats more prey - Prey population decreases - Death rate of prey > birth rate

3 - Predator population no longer supported by reduced prey population - Intraspecific competition occurs - Predator population decreases

4 - Reduced predator population
results in less prey being killed - More prey survives and reproduce

20
Q

Explain why predator-prey relationships in the wild may not follow the pattern described above

A
  • Prey not only food source - Predator can get energy by eating another animal(s) - Decrease in particular prey may not cause decrease in predator population
  • Predators contract a fatal disease - Prey population increases dramatically
  • Natural disaster - Destroys both populations
  • Seasonal fluctuations - e.g. larger plant growth in summer - Increases prey food source so population increases
21
Q

Define conservation

A
  • Maintenance of biodiversity
  • Through sustainable human management
22
Q

Define preservation

A

Protection of an area by restricting human interference

23
Q

Describe the differences between conservation and preservation

A
  • Conservation maintains ecosystem
  • Involves sustainable management of ecosystem
  • Preservation leaves ecosystems undisturbed
24
Q

Outline the reasons for conserving biological resources

A
  • Aesthetic / recreational value
  • Ecotourism
  • To preserve biodiversity and genetic diversity
  • Natural resources could be useful as potential for medicines
  • To support indigenous people
  • To stop effect of deforestation on climate
  • Moral responsibility for future generations
25
Q

Define sustainable resource

A
  • Renewable resource
  • Economically exploited in a way that it will not run out
26
Q

What are the aims of sustainability?

A
  • Preserve the environment
  • Ensure resources available for future generations
  • Enable LEDCs to develop
  • Create more even balance between LEDCs and MEDCs in the consumption of resources
27
Q

Explain how small-scale timber production can be managed in a sustainable way

A

Coppicing
- Cutting tree stems close to ground
- New shoots form from cut surface

Pollarding
- Cutting stem higher from ground
- Prevents animals eating shoots

Rotational coppicing
- Coppicing different areas each time, to allow time for growth
- Maintains biodiverstiy

28
Q

Explain how large-scale timber production can be managed in a sustainable way

A

Selective cutting
- Only largest trees removed

Replace trees through replanting
- Biodiversity, mineral and water cycles maintained

Plant trees optimal distance apart
- Reduces competition, increase yield

Ensure areas of forest remain for indigenous people

29
Q

Explain how fish stocks can be managed in a sustainable way

A

Preventing overfishing
- Applying quotas
- Restricting fishing times throughout year

Mesh size increased in fishing nets
- Only mature fish caught, so breeding can continue

30
Q

How can ecosystems be managed to protect species and habitats?

A
  • Control number of tourists/visitors
  • Involvement of local communities
  • Education of local communities
  • Control the introduction of species
31
Q

Define ecotourism

A
  • Tourism directed towards natural environments
  • Supports conservation
32
Q

What are the key principles of ecotourism?

A
  • Ensure tourism does not exploit natural environment or local communities
  • Engage with local communities on planned developments
  • Ensure infrastructure improvements benefit local communities
33
Q

What are the negative effects of ecotourism?

A
  • Increased erosion of walking trails
  • Increased use of 4x4 vehicles
  • Causes soil erosion and habitat changes
34
Q

Give three regions where there is a conflict between conservation and human needs

A
  • Masai Mara region (Kenya)
  • Terai region (Nepal)
  • Peat bogs (UK)
35
Q

Describe the ecosystem of the Masai Mara region

A

Savannah
- Open grasslands with occasional shrub and trees

36
Q

State and explain the positive impacts of tourism on the Masai Mara region

A
  • People bring economic input into region, which creates jobs and enables region to invest in infrastructure
  • Visitors see local tribes, which educates visitors about their traditional way of life
  • Research carried out in the Masai Mara, which ensures maintenance of biodiversity in the region
37
Q

State and explain the negative impacts of tourism on the Masai Mara region

A

Large visitor numbers requires infrastructure
- Can damage environment and uses natural resources

Visitors require transportation
- Leads to soil erosion and increases pollution

38
Q

Describe the ecosystem of the Terai region

A
  • Mixture of fertile agricultural land, with densely forested regions
  • Hot and humid in the summer months
  • Subjected to monsoons
39
Q

How do humans use the Terai region?

A
  • Agriculture
  • Forestry
  • Tourism
40
Q

Describe the sustainable forestry practices used in the Terai region

A

Local community forestry groups established
- Set agreed prices for timber and reinvest profits for benefit of local population

Sustainable forestry practice has increased forested area
- Larger region available to support biodiverse ecosystem
- Provided improved economic income to the region

41
Q

Describe the sustainable agriculture practices used in the Terai region

A

Sustainable agriculture has prevented further intensive agriculture in region
- Retained biodiversity of less cultivated regions
- Improved irrigation of land
- Encouraged multiple cropping to improve fertilisation of land

42
Q

Describe the ecosystem of peat bogs

A

Spongy, waterlogged land containing decomposing vegetation

43
Q

Why are peat bogs under threat?

A
  • Peat used for fuel and as soil additive
  • Peat removed from land to supply human demands
  • Intensive farming and irrigation has removed water from wetlands
44
Q

Describe the conservation measures used to protect the peat bog ecosystem

A
  • Maintain water levels by reducing drainage from land
  • Removal of tree seedlings from area to prevent water removal
  • Using controlled grazing to maintain biodiversity of peatland surface
45
Q

Describe the effects of human activities on animal and plant populations in the Galapagos Islands

A
  • Increased demand for resources (e.g. water, energy) due to increased tourism
  • Waste and pollution increased
  • Overfishing has endangered sea-life (e.g. sea cucumbers)
  • Many non-native species have been introduced
  • Outcompete the native species
46
Q

Describe the conservation projects put in place in the Galapagos Islands

A

Goat culling to eliminate non-native species
- Increases vegetation
Giant tortoises bred in captivity
- Increases population size

Biology Paper 2 (13 decks)

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