Biology - variation

Question 1

natural selection and evolution

Answer 1

genetic variation due to mutations
variation refers to differences between organisms of same species

Question 2

Charles Darwin and natural selection

Answer 2

theory states that organisms who are better adapted to their environment are more likely to survive and produce offspring. this means that, over time, their genes and characteristics will become more common in the population

Question 3

example how crab population has evolved by means of natural selection

Answer 3

1. some crabs have sharper pincers which help them grab even the toughest shellfish
2. sharp pincers have an advantageous allele, because they are able to eat more. better fed = survive longer = reproduce more
3. overtime, greater proportion of crabs in population have better-adapted allele that produces sharper pincers
4. smaller proportion has allele that causes shorter pincers because they have less success reproducing

Question 4

antibiotic resistance

Answer 4

1. within bacteria population there is variation due to mutations
2. one mutation provides resistance to certain antibiotics
3. when selection pressure of antibiotics is used, the bacteria with this beneficial allele will survive
4. they will reproduce and pass these advantageous alleles on, until the number of bacteria which are resistant increase

Question 5

genetic sources of variation

Answer 5

genes passed on from parents to offspring via gametes
each individual is genetically unique because they have inherited genes from each of their parents, in a random combination
examples: eye colour, blood group, genetic disorders

Question 6

environment sources of variation

Answer 6

environment can also cause members of the same species to show different characteristics