3.1.11 Biodiversity within a Community Flashcards Preview

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Flashcards in 3.1.11 Biodiversity within a Community Deck (26)
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What is genetic diversity?

Differences in the DNA of organisms


Name and explain 2 ways in which genetic diversity can be increased within a population

  • Mutations in DNA
    • Creates new alleles 
  • Gene flow
    • Different alleles being introduced to populations when individuals from another population migrate into them and reproduce


What does genetic diversity allow to occur?

Natural selection


Why is it that a species with a greater genetic diversity is more likely to adapt to an environmental change?

∵ have wider range of alleles = wider range of characteristics

∴ greater probability that some individual will possess a characteristic that's suits the new environmental condition


Genetic diversity can be measured by comparing... (name 3 things)

  • Base sequence of DNA or of mRNA
  • Frequency of specific base sequences or alleles in population
  • Amino acid sequence of encoded proteins


What is a genetic bottleneck?

Event that causes big reduction in population


Describe how genetic bottlenecks reduce genetic diversity

Reduces number of different alleles in gene pool = reduces genetic diversity

(Survivors reproduce and larger population is created from few individuals)


Describe the founder effect

  1. Small group of organisms become separated from main population & found a new colony 
  2. Small group =  small no. of different alleles in initial gene pool and have no choice but to breed with each other 
  3. Decreases the genetic diversity in population 


What does the founder effect occur due to?

Migration (separation of a specie)


Describe how the founder effect may lead to higher incidence of genetic disease (3)

Small colony and one person may carry faulty allele for a genetic disease

  1. Less genetic diversity / smaller gene pool
  2. Individuals breed within group / do not breed with outsiders
  3. Higher chance of inheriting allele



Describe how selective breeding reduces genetic diversity

  • Individuals with desired characteristics are breed together to pass on the desired alleles
  • Variety of alleles within population is deliberately restricted to small no. of desired alleles
  • Leads to population that possess only desired alleles


What is biodiversity?

Variety of living organisms in an area


Define species richness 

No. of different species in a community


Define species evenness 

Abundance of each species 


State the formula for the index of diversity & state what each symbol/letter represents 


The higher the index of diversity, the more...

diverse the area is = habitat is more likely to withstand any change


If all individuals are of same species, the index is ___



Name 5 agricultural practices that can reduce biodiversity

  1. Woodland clearance - to increase area of farmland
  2. Hedgerow removal - increase area of farmland turning lots of small fields into fewer large fields
  3. Pesticides - chemicals that kill organisms (pests) that feed on crops
  4. Herbicides - chemicals that kill unwanted plants (weeds)
  5. Monoculture - fields containing only one type of plant


Describe how woodland clearance reduces biodiversity

  • Fewer plant species 
  • Less habitats and less food sources 
  • Species will die or migrate = reducing biodiversity


Describe how pesticides reduce biodiversity

  • Reduces diversity = directly killing pests
  • Species that feed on pests = lose food source ∴ their numbers decrease


Describe how monoculture reduces biodiversity

Single type of plant - reduces biodiversity directly & supports fewer organisms (e.g. as habitat/food source) reduces further biodiversity


Name 4 examples of incentives/restrictions to encourage sustainable agriculture

  • Financial incentives from governments to introduce features e.g. buffer strips
  • Financial incentives (tax relief) for restoring/managing areas of woodland that been deforested for farming
  • Restricting expansion of agricultural land in favour of improving productivity in current areas
  • Removing subsides for production 


Give 2 conservation schemes examples

  • Giving legal protection to endangered species
  • Creating protected area = restrict further development




Explain why it may be more useful to calculate the index of diversity than to record only the number of species present (2)

  • Measures number of individuals of each species & number of species
  • Some species may be present in low/high numbers


The points on the graph have been joined with straight lines rather than with a smooth curve. Explain why.

Cannot predict/don't know the intermediate values 

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