1.6 Evolution

Question 1

evolution

Answer 1

changes in organisms over generations as a result of genomic variations

Question 2

changes to the gene pool arise by

Answer 2

• gene transfer
• natural selection
• speciation

Question 3

natural selection

Answer 3

the non random increase in frequency of DNA sequences that increase survival and the non random reduction in the frequency of deleterious sequences

Question 4

types of selection

Answer 4

• stabilising
• directional
• disruptive

Question 5

stabilising selection

Answer 5

• an average phenotype is selected for and extremes are selected against
• eg. blonde hair + black hair = brown hair

Question 6

directional selection

Answer 6

• one extreme of the range is selected for
• eg. big bear + small bear = big bear

Question 7

disruptive selection

Answer 7

• two or more phenotypes are selected for
• eg. black cat + white cat = black and white cat

Question 8

horizontal gene transfer

Answer 8

where genes are transferred between individuals in the same generation

Question 9

vertical gene transfer

Answer 9

where genes are transferred from parent to offspring as a result of sexual or asexual reproduction

Question 10

is natural selection most rapid in prokaryotes or eukaryotes? why?

Answer 10

• prokaryotes
• because they can transfer genetic material horizontally, which is an instantaneous process
• this results in faster evolutionary change

Question 11

species

Answer 11

a group of organisms capable of interbreeding to produce fertile offspring, and which do not normally breed with other groups.

Question 12

speciation

Answer 12

the generation of new biological species by evolution as a result of isolation, mutation and selection

Question 13

Allopatric speciation

Answer 13

• caused by geographical barriers
• eg. continental drift, mountain ranges

Question 14

Sympatric speciation

Answer 14

• caused by ecological or behavioural barriers
• eg. mating practices, different habitats