2021 · Paper 2 · Question 4 · 9 marks
SaveMale fruit flies are more likely than female fruit flies to have white eyes.
Explain why.
A female fruit fly with white eyes was crossed with a male fruit fly with red eyes to produce a large number of offspring.
Tick (✓) one box next to the statement which correctly describes the phenotypes produced from this cross.
☐ Equal numbers of red-eyed males and white-eyed males
☐ Equal numbers of red-eyed females and white-eyed females
☐ Equal numbers of red-eyed males and red-eyed females
☐ Equal numbers of white-eyed males and white-eyed females

Explain the results in Table 2.
The first generation of a population of fruit flies had 50 females.
Calculate how many female fruit flies would be produced from this population in the fifth generation.
You can assume: each female produces 400 offspring each generation, half the offspring produced each generation are female, there is no immigration or emigration, no flies die before reproducing.
Show your working.
Give your answer in standard form.