evolution aq

Question 1

larger brains are better at identifying predators
scientists found that only female guppies were attracted to the male guppies bright in colour, suggest and explain an advantage of this colour

Answer 1

-females with larger brains will mate with males bright in colour.
-male offspring more likely to be bright in colour
-bright colour could attract larger brained females
-the population could evolve to have bigger brains
-the population are better at avoiding predators

Question 2

describe how the behaviour of female guppies could result in sympatric speciation

Answer 2

• not geographically isolated
• leading to reproductive isolation
  -gene pools kept separate
  -change in allele frequencies so cannot breed to produce fertile offspring

Question 3

desribe how farming cattle as a source of milk could have led to the allele producing lactase being more prominent

Answer 3

-allele due to mutation
-milk provides named nutrient e.g. glucose
-individuals with the advantageous allele more likely to survive and reproduce
-directional selection
-frequency of allele increases

Question 4

two flowers on an island flower at different times and they used to be part of the same species, suggest how these two species arose by sympatric speciation

Answer 4

-occurs in same habitat/ environment
-mutation causes different flowering times
-reproductive separation/ isolation
-no gene flow
-gene pools remain separate
-different alleles passed on/ selected OR changes in frequency of alleles
- disruptive natural selection.
-eventually, different species cannot interbreed to produce fertile offspring
-are not geographically isolated

Question 5

explain how isolated giraffes may have evolved from a common ancestor

Answer 5

-gene pool separate/ no interbreeding
-mutation linked to different markings/ colours
-selection/ survival linked to different mutations/ colours
- adapted organisms breed and there is reproductive success
-change in allele frequencies