32. In human males, autosomal and sex trisomy mains occurs due to-
(1) Error in meiosis
(2) Non-disjunction of chromosome
(3) Dominant Y chromosome
(4) Faulty Repair mechanism

Option-wise explanation

1. Error in meiosis

• Too vague. Trisomy is a very specific kind of meiotic error: failure of chromosomes to separate. Many different “errors in meiosis” exist, but the textbook term for trisomy origin is nondisjunction.

2. Non-disjunction of chromosome – correct

• Trisomy occurs when a pair of homologous chromosomes (meiosis I) or sister chromatids (meiosis II) fails to separate, so one gamete gets two copies and the other gets none.

• Fusion of such an n+1 gamete with a normal n gamete produces a 2n+1 zygote (autosomal or sex-chromosome trisomy).

3. Dominant Y chromosome

• The Y chromosome carries male-determining genes (like SRY) but is not “dominant” in a way that explains trisomy. It does not cause an extra copy of any chromosome.

4. Faulty repair mechanism

• DNA repair defects can cause mutations or structural rearrangements, but numerical chromosome abnormalities like trisomy are specifically due to mis-segregation (nondisjunction), not repair failure.

So, autosomal and sex-chromosome trisomies in human males mainly result from chromosomal non-disjunction (option 2).