Apentix/AP Biology/Unit 6: Gene Expression and Regulation/Question
AP Biologyeasymcq1 pt

Which statement correctly distinguishes exons from introns in a eukaryotic gene?

A.Introns are copied by RNA polymerase while exons are skipped entirely during transcription
B.Both regions are transcribed, but introns are excised before the mature mRNA is translated
C.Exons are removed during processing so that introns alone can encode the protein
D.Only prokaryotic genes contain introns, while eukaryotic genes consist purely of exons

Explanation

Core Concept

Both exons and introns are transcribed into the initial eukaryotic pre-mRNA. During typical RNA processing, introns are removed and exons are joined to form the mature coding transcript. Some genes are intronless and some transcripts show alternative or retained-intron processing, so it is too absolute to say that only fully spliced RNA reaches the cytoplasm or that intronic sequence can never affect protein production.

Correct Answer

BBoth regions are transcribed, but introns are excised before the mature mRNA is translated

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