Drosophila melanogaster was chosen by Thomas Hunt Morgan for the experimental verification of the chromosomal theory of inheritance because of its:
(A) Many types of hereditary variations visible under a low-powered microscope
(B) Large number of progeny in single mating
(C) Clear differentiation of sexes
(D) Life cycle of about 4 weeks
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → (A), (B) and (C) only
(A) Many types of hereditary variations visible under a low-powered microscope — A reason. The variations are easy to see and score.
(B) Large number of progeny in single mating — A reason. Many progeny flies give reliable ratios.
(C) Clear differentiation of sexes — A reason. The male and female flies are easily distinguishable.
(D) Life cycle of about 4 weeks — Not a reason as stated. The fly completes its life cycle in about two weeks, not four.
NCERT Extract:
Chromosomal Theory of Inheritance – “… Morgan worked with the tiny fruit flies, Drosophila melanogaster (Figure 4.10), which were found very suitable for such studies. They could be grown on simple synthetic medium in the laboratory. They complete their life cycle in about two weeks, and a single mating could produce a large number of progeny flies. Also, there was a clear differentiation of the sexes – the male and female flies are easily distinguishable. Also, it has many types of hereditary variations that can be seen with low power microscopes.”
Figure 4.10 Drosophila melanogaster (a) Male (b) Female