Which of the following statements is not correct about heterochromatin?
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → It is transcriptionally active.
Chromatin in the nucleus is not packed evenly. Regions that are loosely packed stain light and are called euchromatin; regions that are densely packed stain dark and are called heterochromatin. Euchromatin is transcriptionally active, while heterochromatin is inactive.
Option (1) It is densely packed. — A correct statement. Heterochromatin is the more densely packed chromatin.
Option (2) It is transcriptionally active. — An incorrect statement. Heterochromatin is transcriptionally inactive. It is euchromatin that is transcriptionally active, so this is the answer.
Option (3) It is darkly stained. — A correct statement. Because it is densely packed, heterochromatin stains dark.
NCERT Extract:
Packaging of DNA Helix – “… In a typical nucleus, some region of chromatin are loosely packed (and stains light) and are referred to as euchromatin. The chromatin that is more densely packed and stains dark are called as Heterochromatin. Euchromatin is said to be transcriptionally active chromatin, whereas heterochromatin is inactive.”