, distinguish between heterogametic and homogametic sex determination system

Asked by gheethaswamy38 | 27th Nov, 2019, 10:31: PM

Expert Answer:

Types of sex determination systems:

Depending on the presence of similar gametes (homogametic) or dissimilar gametes (heterogametic), following are the systems of sex determination:

XX-XY type:

  • Females are homogametic as they produce only one type of egg, (A+X).
  • Males are heterogametic as they produce two types of sperms, (A+X) and (A+Y).
  • The sex ratio produced in the progeny is 1:1.
  • Examples: Most insects like fruitfly Drosophila and mammals including human beings.

XX-XO type:

  • Females are homogametic, (A+X).
  • Males are heterogametic (A+X) and (A+O).
  • The sex ratio produced in the progeny is 1:1.
  • Examples: Roundworms and some insects such as true bugs, grasshoppers and cockroaches.

ZW-ZZ type:

  • Females are heterogametic, (A+Z) and (A+W).
  • Males are homogametic, (A+Z).
  • The sex ratio produced in the progeny is 1:1.
  • Examples: Birds and some reptiles.

ZO-ZZ type:

  • Females are heterogametic, (A+Z) and (A+O).
  • Males are homogametic, (A+Z).
  • The sex ratio produced in the progeny is 1:1.
  • Examples: Butterflies and moths.

Answered by Sheetal Kolte | 28th Nov, 2019, 11:08: AM