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Biology · 2026 · 2 marks
CBSE 2026 · Region 5 · Set 2 · Q21
One of the salient features of the genetic code is that it is nearly universal from bacteria to humans. Mention two exceptions to this rule. Why are…
One of the salient features of the genetic code is that it is nearly universal from bacteria to humans. Mention two exceptions to this rule. Why are some codes said to be degenerates ?
Marking-scheme solution
The exceptions are found is -
(a)(i)
mitochondrial codons.
(ii)
some protozoans.
Some codes are said to be degenerate because some amino acids are coded by more than one codon.
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CBSE Class 12 Biology past-paper question from the 2026 board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.