Multiple choice

With reference to sex determination in Melandrium album, consider the following statement:

  1. The Y chromosome is longer than the X chromosome.

  2. The Y chromosome and X chromosome form a heteromorphic bivalent at meiosis.

  3. It is the presence of a single Y chromosome rather than any number of X chromosomes or autosomes that give a male individual.

Which of the statements given above are correct?

  1. 1 and 2 only

  2. 2 and 3 only

  3. 1 and 3 only

  4. 1,2 and 3
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

In Melandrium album (now classified as Silene latifolia), the Y chromosome is longer than X, they form heteromorphic bivalents, and the presence of a Y chromosome determines maleness regardless of the number of X chromosomes. Statement 2 is incorrect because Y and X are heteromorphic (different in size and structure), not homomorphic.

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