Natural selection

Question 1

define: natural selection

Answer 1

process by which new heritbale traits evolve and persist in a population.

Question 2

define selecting agent/selection pressure

Answer 2

• Factor making one organism more/less likely to survive and pass on its genes

Question 3

when a phenotype has a higher fitness value/selection advtangage…

Answer 3

it is more likely to survive, therefore more likely to reproduce

Question 4

natural selection can result in

Answer 4

formation of subspecies/species

Question 5

process of natural selection?

Answer 5

There is pre-existing variation in a population that is genetically determined (polymorphic)
A selecting agent makes one form more likely to survice and therefore reproduce than other forms.
The selection pressure continues over a number of successive generations
A change in allele frequency is established.

Question 6

process of artificial selection (selective breeding)?

Answer 6

• 1. Pre-existing variation that is genetically determined.
• 2: Humans choose only organisms displaying a particular trait to reproduce (rather than an environmental selection pressure).
• 3. These organisms and their offspring are bred together over many generations.
• 4. This increases the frequency of this trai

Question 7

advantages of selective breeding?

Answer 7

• Increases the frequency of traits with better economic or aesthetic value

Question 8

disadvantage of selective breeding?

Answer 8

• Increasing the frequency of one trait can increase/decrease allele frequency of other traits (eg. resistance to disease) – so this pop may not be resistant to a particular disease.
• Selectively bred species can replace wild types, reducing biodiversity. If this species goes extinct there might not be wild types to fall back on, leading to food insecurity.