Former genes that have accumulated mutations over a long time and no longer produce a functional protein are called

• A. Exons
• B. Pseudogenes
• C. Introns
• D. Transposons

Answer: (B)

Pseudogenes are former genes that have accumulated mutations over time and no longer produce a functional protein. They’re evolutionary remnants: once-functional genes that drift under little selective pressure, gathering disabling changes like premature stop codons or frameshifts so they can’t make a usable product anymore. Some arise when a gene is duplicated and one copy accumulates mutations, while others come from reverse-transcribed mRNA that gets inserted back into the genome as a processed pseudogene, typically lacking introns and regulatory elements. They aren’t exons (the coding parts of functional genes), nor introns (noncoding parts within genes that are spliced out), nor transposons (mobile genetic elements).