Q.27 Assuming independent assortment and no recombination, the number of different
combinations of maternal and paternal chromosomes in gametes of an organism
with a diploid number of 12 is _________________.

Number of Gamete Combinations for Diploid 12

Diploid number of 12 means 6 pairs of homologous chromosomes, so under independent assortment with no recombination, gametes form ²6=64 unique combinations of maternal and paternal chromosomes.

Correct Answer

The number is 64. Fill-in-the-blank: 64

Explanation

Independent assortment occurs during meiosis I, where each homologous pair aligns randomly at the metaphase plate, allowing maternal or paternal chromosomes to segregate independently into gametes. For 2n=12 (n=6 chromosome pairs), no recombination means whole chromosomes assort as units, yielding 2ⁿ=2⁶=64 distinct combinations per gamete. This follows Mendel’s second law, maximizing genetic diversity without linkage effects.

Why This Formula?

• Haploid gametes receive one chromosome from each of the 6 pairs.
• Each pair has 2 choices (maternal or paternal), so possibilities multiply: 2×2×2×2×2×2=64.
• No recombination ensures chromosomes stay intact, unlike linked genes.
• Example: For 2n=2 (n=1), 2 gametes; for 2n=4 (n=2), 4 gametes—scales exponentially.