LIFECYCLE QUESTIONS

1. The diagram shows the life cycle of a single-celled organism. The zoospores are produced by cell division and are small versions of the adult

(a) Mark with an X on the diagram where meiosis takes place in this life cycle.
(1)
(b)  Explain

(i)

why the zoospores labelled X on the diagram all have the same genotype (genetic constitution)
  • because they are produced by mitosis
  • so receive exact copies of (parental) DNA
(2)

(ii)

why the zoospores labelled W will have a variety of different genotypes
  • because they are produced by meiosis
  • they contain only half the genetic material of the parent cells

(2)

(c) If a zoospore of this organism contained 4 chromosomes. How many chromosomes would you expect to find in

(i)

the gamete from another organism
  • 4

(1)

(ii)

the adult organism
  • 4

(1)

(iii)

the zygote
  • 8
(1)