What is the function of telomerase in chromosome maintenance?

• A. Telomerase cuts telomeres to remove damaged ends.
• B. Telomerase adds telomere repeats to chromosome ends to maintain length.
• C. Telomerase unwinds DNA ahead of the replication fork.
• D. Telomerase polymerizes proteins.

Answer: (B)

The main idea tested here is how telomerase prevents progressive shortening of chromosomes by extending their ends. Telomerase is a ribonucleoprotein that carries its own RNA template and uses reverse transcription to add telomere repeats to the 3’ end of chromosomes. In humans, this means it can lengthen the very ends of DNA so that the subsequent gap-filling by ordinary DNA polymerases restores telomere length after replication. This counteracts the end-replication problem and helps protect genome stability, especially in germ cells and some stem or cancer cells where telomerase activity is higher.

This explains why the statement about adding telomere repeats to chromosome ends to maintain length is the correct description of telomerase’s function. It’s not about cutting telomeres, unwinding DNA at the fork, or making proteins, so those activities don’t describe what telomerase does.