Question

A structure not present in all chromosomes is ______.

Options

• centromere

• chromonemata

• secondary constriction

• telomere

Answer 1

A structure not present in all chromosomes is secondary constriction.

Explanation:

Structures like the centromere, chromonemata, and telomeres are essential components found in all functional chromosomes for stability and replication. In contrast, secondary constrictions are only present on specific chromosomes at fixed locations, where they often function as nucleolar organiser regions (NORs). Chromosomes containing this distinct structure are known as satellite chromosomes (or SAT-chromosomes).