Biology OCR A level: Biodiversity

Define biodiversity.

Define biodiversity.

The variety of living organisms present in an area.

Define habitat biodiversity

The number of different habitats found in an area.

Define species richness.

The number of different species found within an area.

Define species eveness.

A comparison of the number of individuals of each species living in a community.

Define genetic biodiversity.

The variety of genes that make up a species.

Explain genetic biodiversity within a species.

Within a species, individuals mostly have the same genes, however different alleles exist for some genes (polymorphic genes).

What is the benefit of greater genetic biodiversity?

• Better adaptation to changing environments

• More likely to have individuals resistant to diseases.

How would you calculate the biodiversity of a habitat?

Use Simpson’s index.

How can genetic biodiversity of a population increase?

• Random mutations in the DNA to create new alleles

• Migration to transfer alleles

What is gene flow?

The transfer of alleles from a member of one population to a member of another during interbreeding.

How can genetic biodiversity of a population decrease?

• Selective breeding - only animals with advantageous characteristics are allowed to breed. eg. pedigree animals.

• Captive breeding programmes - only a small number of captive individuals of a species can be bred.

• rare breeds (reduced gene pool)

• Artificial cloning - asexual reproduction, using cuttings to clone a plant

• Natural selection - over time, individuals with advantageous alleles survive and other alleles can be lost

• Genetic bottlenecks - if only a few members of a population survive an event, the gene pool is reduced and only the alleles of the survivors can be passed on

• founder effect - A small number of individuals create a new population in a geographically isolated area hence the gene pool is small

• genetic drift - the frequency of occurrence of alleles can vary due to the random nature of inheritance so some alleles can be lost due to chance

What can affect the reliability of a sample?

• Chance

• Sampling bias

Name the 2 types of quadrat.

• Frame

• Point