33. A zygote formed by a fusion of one normal gamete another gamete lacking one due to failure of proper segregated at Anaphase-II will lead into chromosomal aberrations known as
(1) Haploidy         (2) Diploidy
(3) Polyploidy      (4) Aneuploidy

Option-wise explanation:

1. Haploidy

• Haploidy means a single complete set of chromosomes (n), as in normal gametes or haploid organisms.

• Here, the zygote receives n chromosomes from the normal gamete and n−1 from the abnormal gamete, so its chromosome number is not a whole set (neither n nor 2n), but 2n−1 for one chromosome pair.

2. Diploidy

• Diploid cells have exactly two complete sets of chromosomes (2n).

• Because one chromosome is missing from one gamete, the zygote will be missing one copy of that chromosome (e.g., 2n−1, monosomy), so it is not truly diploid.

3. Polyploidy

• Polyploidy involves multiples of the entire set, like 3n (triploid) or 4n (tetraploid).

• Our case changes only one chromosome’s copy number, not the whole set.

4. Aneuploidy – correct

• Aneuploidy is a change in number of one or a few chromosomes, not an entire set (e.g., monosomy 2n−1 or trisomy 2n+1).

• Fusion of a normal gamete (n) with a gamete lacking the chromosome (n−1) yields a zygote with one fewer copy of that chromosome (monosomic), which is a classic example of aneuploidy.