While developing purelines, increased homozygosity results in

The correct answer is Option (3) → accumulation of superior genes

Inbreeding increases homozygosity, which exposes harmful recessive genes so that they can be eliminated by selection.

Option (1) production of superior male only — Incorrect. Homozygosity has no link with the sex of the offspring.

Option (2) aggregation of harmful recessive genes — Incorrect. NCERT says inbreeding exposes harmful recessive genes, which are then eliminated by selection; it does not speak of their aggregation.

Option (3) accumulation of superior genes — Correct. NCERT says inbreeding, by raising homozygosity, also helps in accumulation of superior genes and elimination of less desirable genes.

Option (4) increased fertility — Incorrect. Close inbreeding reduces fertility.

Note: This question is from Chapter 9, Strategies for Enhancement in Food Production, of the pre-rationalised NCERT book. This chapter is not in the present NCERT book (2026-27). The extract below is from the pre-rationalised edition.

NCERT Extract (Pre-rationalised edition, Chapter 9, Strategies for Enhancement in Food Production):
Animal Breeding – “… Try to recollect the homozygous purelines developed by Mendel as discussed in Chapter 5. A similar strategy is used for developing purelines in cattle as was used in case of peas. Inbreeding increases homozygosity. Thus inbreeding is necessary if we want to evolve a pureline in any animal. Inbreeding exposes harmful recessive genes that are eliminated by selection. It also helps in accumulation of superior genes and elimination of less desirable genes. Therefore, this approach, where there is selection at each step, increases the productivity of inbred population. However, continued inbreeding, especially close inbreeding, usually reduces fertility and even productivity. This is called inbreeding depression.”