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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1

What is genetic diversity?

Differences in the DNA of organisms

2

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

3

What does genetic diversity allow to occur?

Natural selection

4

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

5

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

6

What is a genetic bottleneck?

Event that causes big reduction in population

7

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)

8

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 

9

What does the founder effect occur due to?

Migration (separation of a specie)

10

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


     

11

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

12

What is biodiversity?

Variety of living organisms in an area

13

Define species richness 

No. of different species in a community

14

Define species evenness 

Abundance of each species 

15

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

16

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

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

17

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

1

18

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

19

Describe how woodland clearance reduces biodiversity

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

20

Describe how pesticides reduce biodiversity

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

21

Describe how monoculture reduces biodiversity

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

22

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 

23

Give 2 conservation schemes examples

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

24

2.68(6)

25

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

26

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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