Question

Which of the following is correct about bivalent?

(i) Bivalents are tetrads.
(ii) A bivalent means 4 chromatids and 2 centromeres.
(iii) One bivalent consists of 2 homologous chromosomes.
(iv) Bivalents form in zygotene.

• A. (i), (ii), (iii) and (iv)
• B. (iii) only
• C. (iii) and (iv)
• D. (iv) only

Answer 1

The correct option is A (i), (ii), (iii) and (iv)

During the Prophase I of meiosis I the paring of homologous chromosomes takes place in the zygotene substage, in this phase the chromosomes appear to have two chromatids each, attached by a centromere. Therefore the homologous pair appears to have two centromeres and four chromatids also referred to as the bivalents or the tetrads.

So, the correct answer is '(i), (ii), (iii) and (iv)'