Question

The homologous chromosomes align independently at the equator during meiosis so a. all possible combinations of alleles can occur in the gametes. b. only the parental combinations of gametes can occur in the gametes. c. only the nonparental combinations of gametes can occur in the gametes.

Short answer

The correct statement that describes the impact on allele combinations in gametes is option (a) - all possible combinations of alleles can occur in the gametes. This is due to the independent alignment of homologous chromosomes during meiosis, which ensures any possible combination of maternal and paternal chromosomes can be found in the resulting haploid gametes, contributing to genetic diversity in sexually reproducing organisms.

Step-by-step solution

Recall the process of meiosis

Meiosis is a type of cell division that occurs in sexually reproducing organisms, resulting in the formation of haploid gametes (sperm and egg cells). It consists of two rounds of cell division, meiosis I and meiosis II, which ultimately produce four genetically unique, haploid daughter cells. The key steps in meiosis include the pairing of homologous chromosomes, crossing over, and the independent alignment of homologous chromosomes at the equator.

Understand the independent alignment of homologous chromosomes

During meiosis I, particularly the metaphase I stage, homologous chromosomes (each comprising two sister chromatids) align along the cell equator but independently of each other. This random alignment ensures that each gamete has a different combination of maternal and paternal chromosomes, leading to genetic diversity among offspring.

Evaluate each statement (a, b, and c) regarding allele combinations in gametes

a. all possible combinations of alleles can occur in the gametes - This statement is correct. Due to the independent alignment of homologous chromosomes during meiosis, any possible combination of maternal and paternal chromosomes can be found in the resulting haploid gametes. This process contributes to the high degree of genetic variation observed in sexually reproducing organisms. b. only the parental combinations of gametes can occur in the gametes - This statement is incorrect. While parental combinations of chromosomes can occur in the gametes, the independent alignment of homologous chromosomes ensures that a variety of different combinations (including non-parental ones) will also be present in the gametes. c. only the nonparental combinations of gametes can occur in the gametes - This statement is also incorrect. Although nonparental combinations of chromosomes are indeed possible due to the independent alignment of homologous chromosomes, this doesn't exclude the possibility of parental combinations occurring as well.

Conclusion

Based on the understanding of meiosis and the independent alignment of homologous chromosomes, the correct statement that describes the impact on allele combinations in gametes is option (a) - all possible combinations of alleles can occur in the gametes. This process contributes to the genetic diversity observed in sexually reproducing organisms.