natural selection

Question 1

natural selection

Answer 1

• no agent involved - survival of the fittest - the process where individuals with certain inheritable traits survive and reproduce successfully then other individuals leading to evolutionary change in the population

Question 2

gene pool

Answer 2

sum of all alleles in a population at one time - high biodiversity = better chance of population survival - low biodiversity = high chance of extinction

Question 3

stabilising selection

Answer 3

• selecting against the extremes

Question 4

directional selection

Answer 4

• trait shifts in one direction
• selective pressues favouring certain traits

Question 5

disruptive selection

Answer 5

• favours extremes
• 2 peaks form

Question 6

• no agent involved - survival of the fittest - the process where individuals with certain inheritable traits survive and reproduce successfully then other individuals leading to evolutionary change in the population

Answer 6

natural selection

Question 7

sum of all alleles in a population at one time - high biodiversity = better chance of population survival - low biodiversity = high chance of extinction

Answer 7

gene pool

Question 8

• selecting against the extremes

Answer 8

stabilising selection

Question 9

• trait shifts in one direction
• selective pressues favouring certain traits

Answer 9

directional selection

Question 10

• favours extremes
• 2 peaks form

Answer 10

disruptive selection

Question 11

variation

Answer 11

individuals in a population express a range of different phenotypes. members of a population have variation in genotypes that cause variation in their phenotypes. this genetic variation is inheritable, it can be passed onto the next gerneration and in some circumstances may give an individuals an advantage in survival

Question 12

peppered moth

Answer 12

before industrial revolution

• trees were light
• most moths were light (better camoflagued)
• dark moths stood out so were eaten
• selection pressue = predators

industrial revolution

• factories pumped out smoke and soot
• tree bark became dakr
• black moths now camoflagued and had the advantage

Question 13

changes in allele frequency

Answer 13

allele frequency will stay the same unless there are mutations, migration, random genetic drift, natural selection and non - random mating

Question 14

migration

Answer 14

immigration: moving into a population
emigration: moving out of a population
- reduces the differnces between populations because te gene pool becomes more similar

Question 15

random genetic drift

Answer 15

• slow random changes in allele frequency in gene pools due to chance

founder effect: small group of individuals may migrate away or becoe isolated from a population

• the founding population is only made up of a small number of individuals
• certain alleles may be lost resulting in a loss of genetic diversity
• colonising population may evolve differently
• eg islands colonised from the mainland

population bottlenecks: sharp fall in population due to environmental disasters

• allele frequency changes in survivors some alleles are lost, less individuals available for breeding, population more vulnerable

human bottleneck: epidemic, pandemic, earthquake