Independent assortment leads to equal proportions of all possible gametes when?

• A. Alleles assort independently and gametes are formed in equal proportions.
• B. Alleles segregate randomly if alleles are linked.
• C. Crossing over does not occur.
• D. Linkage groups always co-segregate.

Answer: (A)

Independent assortment is at play when different gene loci segregate into gametes without influencing each other. If the two loci are unlinked (on different chromosomes or far apart so they effectively behave independently), the four possible gamete genotypes—AB, Ab, aB, and ab—occur with equal probability, each 1/4. That equal distribution reflects that each allele from one gene combines with each allele from the other gene in all possible ways with the same chance.

If the loci are linked, they tend to stay together during meiosis, so parental combinations appear more often and the equal 1/4 frequencies disappear. Crossing over can create recombinants, but unless recombination is effectively 50% (making the loci behave independently), the four gamete types won’t be produced in equal proportions. Likewise, if a linkage group co-segregates consistently, you’d mainly see parental types rather than all four equally.

So the statement that leads to equal proportions of all possible gametes is that alleles assort independently and gametes are formed in equal proportions.