191. Given below are two statements:
Statement I: Polycistronic mRNAs are found in archaea and bacteria.
Statement II: Plastid genes in eukaryotes have only mono-cistronic mRNA.
In the light of the above statements, choose the most appropriate answer from the options given
below:
A. Both Statement I and Statement II are correct.
B. Both Statement I and Statement II are incorrect.
C. Statement I is correct but Statement II is incorrect.
D. Statement I is incorrect but Statement II is correct.

Explanation:

✅ Statement I: Polycistronic mRNAs are found in archaea and bacteria.

• True.

• In both bacteria and archaea, genes that are functionally related are often organized into operons, which are transcribed as polycistronic mRNA (single mRNA encoding multiple proteins).

• This is a hallmark of prokaryotic gene expression.

❌ Statement II: Plastid genes in eukaryotes have only mono-cistronic mRNA.

• False.

• Plastids (such as chloroplasts) have prokaryotic origins (endosymbiotic theory) and retain several prokaryotic features — including the ability to produce polycistronic mRNA.

• Many chloroplast genes are indeed transcribed as polycistronic units, especially those involved in photosynthesis.

Conclusion:

• While Statement I is accurate regarding prokaryotes, Statement II is incorrect because plastids can produce polycistronic mRNA.