variation and evolution - variation

Question 1

what is variation?

Answer 1

all the differences in the characteristics of individuals in a population

Question 2

what are the three main causes of variation?

Answer 2

• alleles that individuals have inherited. genetic causes. (hair colour and eye colour)
• environment (colours of some flowers depend on the pH of the soil. language in humans)
• combination of genes and the environment. (height in humans. some have alleles to grow taller but diet must have enough calcium to grow bones fully.)

Question 3

what is the genetic variation in a population of species caused by?

Answer 3

mutations which are random changes to DNA and take place all the time. most of the time they don’t have an affect on the phenotype. some mutations can influence phenotype like alleles for tallness may lead to tallness if a person’s diet is suitable. small number of mutations develop phenotype

Question 4

very rarely, mutation can lead to a….

Answer 4

new phenotype. sometimes the new phenotype is beneficial if environment changes which can lead to rapid change in species
example: 1950s virus spread to wild rabbits killing 99% but a mutation occurred making surviving rabbits resistant. this is a beneficial phenotype which is now widespread in UK rabbit population