Question

Multiple alleles are present

• A. at the same locus of the chromosome
• B. on non-sister chromatids
• C. on different chromosomes
• D. at different loci on the same chromosome.

Answer 1

The Correct Option is A

In biology, the concept of multiple alleles pertains to the different forms of a gene that can be found within a population. Let's analyze each option to determine where multiple alleles are present:

1. At the same locus of the chromosome: This statement is correct. Multiple alleles refer to the presence of more than two alleles at a specific locus of a chromosome within a population. A classic example of multiple alleles is the ABO blood group system in humans, where three alleles (I^A, I^B, and i) exist at the same locus on the chromosome.
2. On non-sister chromatids: This option is incorrect. Non-sister chromatids are not involved in the presence of multiple alleles since they pertain to different homologous chromosomes that carry different genes.
3. On different chromosomes: This option is incorrect. Alleles that are on different chromosomes do not represent multiple alleles because they do not occupy the same locus, therefore they affect different characters.
4. At different loci on the same chromosome: This is incorrect. If alleles exist at different loci on the same chromosome, they are affecting different traits, not representing multiple alleles.

Thus, the correct option is: at the same locus of the chromosome. This is because multiple alleles refer to the variations of a gene found at one genetic location (locus) on the chromosome.