SSC CGL 2024 Tier-I · 26 September 2024, Shift 1 · General Awareness · Question 2 of 100

Text as printed on a candidate's response sheet for this shift; answer per SSC's tentative key as marked on that sheet. Solution last reviewed 10 September 2026.

Where this paper and its answers come from

SSC does not publish CGL question papers or a public answer key. The questions and options here are reproduced as printed on a candidate's own response sheet for this shift — the Commission's text, unchanged. Each answer is SSC's tentative key as marked on that sheet; SSC allowed challenges to it and never publishes a final key. The solutions are written by UnlockIAS.

In the context of cell division, which chromosomal behaviour takes place at the leptotene stage?

(a)Chromosomes begin to condense
(b)Synapsis is complete
(c)Homologous chromosomes pair
(d)Chromosomes are un-synapsed

Answer

Why

Correct — A. Leptotene is the first sub-stage of prophase I, and the event it is named for is compaction: chromosomes become visible as long, slender threads and begin to condense.

Nothing has paired yet. Pairing belongs to the next sub-stage and crossing over to the one after that.

So the behaviour that defines leptotene is the onset of condensation — option (a).

Why the others are wrong

(b)
Synapsis is complete — Synapsis finishes at the end of zygotene, so by pachytene the homologues are already fully paired bivalents. Completed synapsis is two sub-stages past leptotene.
(c)
Homologous chromosomes pair — Pairing of homologous chromosomes is zygotene, when the synaptonemal complex forms between them. Leptotene ends before any homologue has found its partner.
(d)
Chromosomes are un-synapsed — Un-synapsed is a state, not an event. Leptotene chromosomes are unpaired, but so are they in diplotene once the synaptonemal complex dissolves, so it identifies nothing.

Concept

Meiosis I opens with the longest prophase in the cell cycle, and NCERT splits it into five named sub-stages: leptotene, zygotene, pachytene, diplotene, diakinesis.

Each is defined by one event. Leptotene condenses, zygotene pairs, pachytene exchanges, diplotene shows the chiasmata, diakinesis terminalises them.

Questions of this shape either give the stage and want the event, or give the event and want the stage. Learn the sequence as a chain of events rather than five words in order.

The stem asks for a chromosomal "behaviour", and that word is the hint. It wants the event that happens at leptotene, not a description that merely happens to be true there.

Key facts

Prophase I of meiosis runs leptotene, zygotene, pachytene, diplotene, diakinesis, in that order.
Synapsis begins in zygotene and the synaptonemal complex forms alongside it.
Crossing over occurs in pachytene, on fully synapsed bivalents, at recombination nodules.
Chiasmata become visible in diplotene as the synaptonemal complex dissolves.

Study next

The five sub-stages of prophase I and the one event each is named forMeiosis I versus meiosis II, and which of the two is the reductional divisionCrossing over, recombination nodules, and why synapsis must precede them

Common traps

Choosing pairing of homologous chromosomes because pairing is the famous event of prophase I. That is zygotene.
Reading un-synapsed as an event when it only describes the stage.

Cell division is asked as stage-to-event recall straight out of the NCERT Class XI chapter. Prophase I suits SSC because its five sub-stage names supply four ready-made options with no arithmetic.

Related PYQs

No directly related past PYQ was found.