- A Largely permanent silencing of both X chromosomes occurring within most cell as generally observed
- B Random inactivation of one X in each somatic cell (forming Barr body), creating cellular mosaicism
- C Consistent inactivation of mainly the maternally inherited X chromosome each time in typical laboratory settings
- D Inactivation of both X chromosomes occurring specifically within male individuals under usual circumstances
Correct answer: B. Random inactivation of one X in each somatic cell (forming Barr body), creating cellular mosaicism
Explanation: Lyon hypothesis: one X is randomly inactivated per female somatic cell, forming a Barr body (inactive X condensed). Each cell expresses either maternal or paternal X alleles.
Concept context
Mendel's laws, inheritance patterns, DNA structure, and molecular biology. Core of NEET biology.
Read the full Principles of Inheritance and Variation notes →