Question Bank [2022] — BIOLOGY STD 12 Science — Question

1. A typical chromosome consists of two chromatids joined together at the centromere also known as primary constriction.
2. Primary constriction consists of a disk shape plate called the kinetochore. During cell division, spindle fibers get attached to the kinetochore.
3. Apart from primary constriction, a few chromosomes possess an additional one or two constrictions called secondary constriction.
4. At secondary constriction I (nucleolar organizer), nucleolus becomes organized during interphase.
5. A satellite body (SAT body) is attached at secondary constriction II, in very few chromosomes.
6. Each chromatid in turn contains a long, unbranched, slender, highly coiled double-stranded DNA thread, called chromonema, extending through the length of the chromatid.
7. The ends of chromosomes (i.e. chromatids) are known as telomeres.

A: Parts of chromosomes
B: Showing secondary constrictions and details
Structure of Chromosome