Question: 100% NCERT covered from Particular Keyword.Explanations are 100% from NCERT | [Difficult level: Easy] From NCERT NEET Derived Question.
Assertion : Chiasmata is formed during diplotene.
Reason : Chiasmata are formed due to deposition of nucleoproteins.
(a) If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion.
(b) If both Assertion and Reason are true but the Reason is not the correct explanation of the Assertion.
(c) If Assertion is true but Reason is false.
(d) If both Assertion and Reason are false.
Answer: (c) If Assertion is true but Reason is false.
The beginning of diplotene is recognised by the dissolution of the
synaptonemal complex and the tendency of the recombined
homologous chromosomes of the bivalents to separate from each other
except at the sites of crossovers. These X-shaped structures, are called
chiasmata. In oocytes of some vertebrates, diplotene can last for
months or years.
The final stage of meiotic prophase I is diakinesis. This is marked by
terminalisation of chiasmata. During this phase the chromosomes are
fully condensed and the meiotic spindle is assembled to prepare the
homologous chromosomes for separation. By the end of diakinesis, the
nucleolus disappears and the nuclear envelope also breaks down.
Diakinesis represents transition to metaphase.