Evolution by Natural Selection

Question 1

What are the environmental causes of Variation?

Answer 1

Climate change: both
Availability of water/ food: animals
Intensity of light, availability of water and nutrients in soil: plants

Question 2

What are the genetic causes of Variation?

Answer 2

Mutation, Meiosis and Fertilisation of Gametes

Question 3

What is the disadvantage of low Genetic Diversity?

Answer 3

populations with low genetic diversity have fewer alleles in the population so they are less likely to have any individuals with characteristics suited to the changes. Low genetic diversity is caused by very small populations or populations where a lot of inbreeding has occurred as both of these reduce the number of alleles

Question 4

What are selection pressures?

Answer 4

predation, disease or competition for resources

Question 5

How doe organisms with variations that make them more likely to survive have a selective advantage?

Answer 5

more likely to reproduce and pass on those alleles to the next generation o these favourable alleles increase in frequency in the gene pool

Question 6

How does natural selection drive evolution?

Answer 6

Variation in a population
Due to mutation some individuals have favourable alleles which help them to survive and reproduce
They pass on these favourable alleles to offspring so the frequency of these alleles in the population increases
If no interbreeding with other population occurs then new species can be formed

Question 7

What is Geographical Isolation?

Answer 7

populations are separated by a physical barrier so no interbreeding can occur