3.1.11 Biodiversity within a Community

Question 1

What is genetic diversity?

Answer 1

Differences in the DNA of organisms

Question 2

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

Answer 2

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

Question 3

What does genetic diversity allow to occur?

Answer 3

Natural selection

Question 4

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

Answer 4

∵ 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

Question 5

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

Answer 5

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

Question 6

What is a genetic bottleneck?

Answer 6

Event that causes big reduction in population

Question 7

Describe how genetic bottlenecks reduce genetic diversity

Answer 7

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

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

Question 8

Describe the founder effect

Answer 8

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

Question 9

What does the founder effect occur due to?

Answer 9

Migration (separation of a specie)

Question 10

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

Answer 10

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

Question 11

Describe how selective breeding reduces genetic diversity

Answer 11

• 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

Question 12

What is biodiversity?

Answer 12

Variety of living organisms in an area

Question 13

Define species richness

Answer 13

No. of different species in a community

Question 14

Define species evenness

Answer 14

Abundance of each species

Question 15

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

Answer 15

Question 16

The higher the index of diversity, the more…

Answer 16

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

Question 17

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

Answer 17

1

Question 18

Name 5 agricultural practices that can reduce biodiversity

Answer 18

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

Question 19

Describe how woodland clearance reduces biodiversity

Answer 19

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

Question 20

Describe how pesticides reduce biodiversity

Answer 20

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

Question 21

Describe how monoculture reduces biodiversity

Answer 21

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

Question 22

Name 4 examples of incentives/restrictions to encourage sustainable agriculture

Answer 22

• 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

Question 23

Give 2 conservation schemes examples

Answer 23

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

Question 24

Answer 24

2.68(6)

Question 25

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

Answer 25

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

Question 26

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

Answer 26

Cannot predict/don’t know the intermediate values