Topic 4.4 - Biodiversity

Question 1

What is biodiversity?

Answer 1

The variety of organisms within an ecosystem

Question 2

Name some ways biodiversity can be measured.

Answer 2

Species diversity - The number of different species and the number of individuals within a community.

Genetic diversity - a measure of genetic variation found in a particular species - i.e. the number of allelles in the gene pool

Ecosystem diversity - The range of different habitats

Question 3

What is the formula for index of diversity?

Answer 3

Question 3

What is meant by the gene pool and allelic frequency?

Answer 3

The gene pool is the number of different alleles and genes within a population. The allelic frequency is how often one allele for one gene may appear in the gene pool.

Question 4

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

Answer 4

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

Question 5

Describe some of the impacts of agriculture can have on biodiversity and how these are being fixed.

Answer 5

Agricultural ecosystems reduce the biodiversity and the number of species present because
humans select for particular characteristics. This therefore reduces the number of alleles
and therefore the genetic diversity of the population. Farmland is typically used for only a
single species and therefore means that fewer individuals of other species can survive there.
In order to maintain biodiversity a number of techniques have been used, some of these
include:
- Using hedgerows instead of fences.
- Growing different crops in the same area, known as intercropping.
- Reducing the use of herbicides and pesticides.
- Preserving wetlands instead of draining these for farming use

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 how selective breeding reduces genetic diversity

Answer 8

• 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 9

Define species richness

Answer 9

No. of different species in a community

Question 10

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

Answer 10

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