18. An individual is having a paracentricinversion (denoted by the region f-e-d, marked by arrows) in homozygous condition.
The meiotic consequences of inversion can be:
A. generation of an acentric and a dicentric
chromosome
B. the recombinants will have long deletion or duplication and may be lethal
C. the inversion will suppress crossing over
D. all gametes will have complete genome and will survive normally
Which of the above statement or their combinations will explain the meiotic consequence of the given inversion logically?
(1) A, B and C (2) A and B
(3) B and C (4) only D
Key idea: homozygous vs heterozygous inversion
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In heterozygotes, one chromosome is normal and the other inverted → inversion loop, abnormal recombinants, crossover suppression.
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In homozygotes, both homologues carry the same inversion, so gene order is identical on both chromosomes. They pair linearly without an inversion loop and behave like normal chromosomes.
Here the individual is homozygous for a paracentric inversion (f–e–d).
Evaluating each statement
A. Generation of an acentric and a dicentric chromosome – Incorrect
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Acentric and dicentric products arise from crossing over in a paracentric inversion heterozygote.
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In a homozygote, the chromosomes are structurally identical; crossing over is normal and does not create acentric/dicentric chromatids.
B. Recombinants will have long deletion or duplication and may be lethal – Incorrect
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Deletions/duplications come from unequal recombination in inversion heterozygotes.
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In homozygotes, recombinants remain balanced; no large deletions/duplications are expected.
C. The inversion will suppress crossing over – Incorrect
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Crossover suppression is again a property of heterozygotes, where abnormal recombinants are eliminated.
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In homozygotes, crossing over occurs freely as in a normal chromosome pair.
D. All gametes will have complete genome and will survive normally – Correct
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Since pairing and recombination are normal and balanced, all gametes receive a complete, structurally balanced genome, so viability is not affected.
Therefore, for a paracentric inversion in homozygous condition, the only logical meiotic consequence given is statement D, so the correct option is (4) only D.
