Question

Mendel’s law of independent assortment when interpreted in a modern context indicates:
A. Alleles are present on the same chromosome, but they assort independently due to recombination.
B. Alleles are present on independent chromosomes and these separate and assort independently.
C. Alleles are present on independent chromosomes and they are sorted independently during meiosis.
D. Alleles are present on the same chromosome and their combination is dependent.

Answer 1

Hint: The Mendel’s law of independent assortment states that alleles of two different genes get sorted into gametes which are independent of each other. In other words, it means that the allele which a gamete receives for one gene does not influence the allele that is received for the other gene. The physical basis for the law of independent assortment lies in the gamete formation of meiosis I, when the homologous pairs line up in random orientations at the middle of the cell while they prepare to separate.

Complete answer:
Option A: Alleles are present on the same chromosome, but they assort independently due to recombination - The genes that are on different chromosomes assort independently, according to Mendel’s law of independent assortment. Genes that are far apart on the same chromosome also assort independently by crossing over, or by exchange of homologous chromosome bits which occurs at an early stage in meiosis I. Since it is given as alleles are present on the same chromosomes.
The option A is not correct
Option B: Alleles are present on independent chromosomes and these separate and assort independently - According to Mendel’s law of independent assortment, the alleles of two different genes get sorted into gametes and are independent of each other and occur during the stage of meiosis I.
Hence option B is not correct.
Option C: Alleles are present on independent chromosomes and they are sorted independently during meiosis - Mendel’s law of independent assortment says that the alleles of two or more different gene pairs assort independently of each other during the stage of meiosis. Here, a random combination of the genes from each of the pairs winds up in the gametes.
Hence option C is the correct answer.
Option D: Alleles are present on the same chromosome and their combination is dependent - In Mendel’s law of independent assortment, alleles are present on different or independent chromosomes and are sorted independently.
Hence option D is not correct.

So, Option C is the correct answer.

Note:
Mendel’s law of independent assortment observations gives that the genes do not influence each other with regard to the sorting of alleles into gametes. The possible combination of alleles for every gene is equally likely to occur. Therefore, the calculation of any particular genotypic combination of more than one gene is the probability of the desired genotype at the first locus multiplied by the probability of the desired genotype on the other loci.