CBSE 2026 · Region 2 · Set 1 · Q23 · 3 marks
(a)Give the scientific name of the organism used by Morgan to study sex-linked traits.(b)Write any four reasons why this organism made it an ideal experimental model.
(a)
Give the scientific name of the organism used by Morgan to study sex-linked traits.
(b)
Write any four reasons why this organism made it an ideal experimental model.
Marking-scheme solution
(a)
Drosophila melanogaster
(b)
$\displaystyle \star$ They could be grown on simple synthetic medium in the laboratory.
$\displaystyle \star$ Complete their life cycle in about two weeks.
$\displaystyle \star$ Single mating produces large number of progeny flies.
$\displaystyle \star$ Clear differentiation of sexes – male and female flies are easily distinguishable.
$\displaystyle \star$ Has many types of hereditary variations that can be seen under low power microscopes.
(Any other correct reason)
Principles of Inheritance and VariationSex DeterminationRemembershort_answereasy
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CBSE Class 12 Biology past-paper question from the 2026board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.