Which of the following is not a salient feature of the human genome?

The correct answer is Option (3) → Chromosome X has most genes, and the Y has the fewest.

The Human Genome Project gave a list of salient features of the human genome. Among them, the largest known gene is dystrophin, repeated sequences make up a very large portion of the genome, and chromosome 1 has the most genes while the Y chromosome has the fewest.

Option (1) The largest known human gene is dystrophin. — A correct statement. Gene sizes vary greatly, and the largest known human gene is dystrophin.

Option (2) Repeated sequences make up a very large portion of the human genome. — A correct statement. Repeated sequences form a very large part of the human genome.

Option (3) Chromosome X has most genes, and the Y has the fewest. — An incorrect statement. The chromosome with the most genes is chromosome 1, not the X chromosome. The Y chromosome does have the fewest genes, but the first part of the statement is wrong, so this is not a feature of the human genome.

Option (4) Repetitive sequences shed light on chromosome structure, dynamics and evolution. — A correct statement. Repetitive sequences are thought to have no direct coding function, but they shed light on chromosome structure, dynamics and evolution.

NCERT Extract:
Salient Features of Human Genome – “… (ii) The average gene consists of 3000 bases, but sizes vary greatly, with the largest known human gene being dystrophin at 2.4 million bases. … (vi) Repeated sequences make up very large portion of the human genome. (vii) Repetitive sequences are stretches of DNA sequences that are repeated many times, sometimes hundred to thousand times. They are thought to have no direct coding functions, but they shed light on chromosome structure, dynamics and evolution. (viii) Chromosome 1 has most genes (2968), and the Y has the fewest (231).”