Question

How would you explain how independent assortment, crossing over and random fertilization contribute to genetic variation?

Answer 1

Hint: Genetic variations are defined as the diversity in the gene frequencies and the differences between the individuals or between the populations. It differentiates the DNA among individuals or populations.

Complete answer:
During Prophase, crossing over takes place in meiosis 1 and during anaphase independent assortment takes place which creates a set of chromosomes that includes new combinations of alleles. A genetic variation that gets introduced by random fertilization of the gametes is produced by the process of meiosis. During sexual reproduction, the genetic variation increases, and the genetically unique sperm gets generated by a male which gets fertilized with the genetically unique egg that is produced by the female. The homologous pairs of chromosomes get aligned along with the metaphase plate in metaphase 1 and this orientation of the homologous pairs is done randomly which is differentiated with every cell that undergoes a process of meiosis. This arrangement includes 23 different tetrads in the human body and each tetrad consists of one maternal and one paternal pair of sister chromatids. This creates $50\%$ chances of the opposite orientation that occurred during metaphase 1 in another cell.

Additional information:
Meiosis is highly regulated and consists of different molecules and proteins that are responsible for the regulation of the steps of the process which occur during the process. It can detrimentally affect the resulting offspring if any mistake can happen during the replication of chromosomes. These errors can occur during the segregation of the chromosomes. Nondisjunction involves the abnormal separation of chromosomes which results in a wrong number of a chromosome that will be attached to each gamete and can cause several human disorders that result in the correct separation and movement of the pairs of homologous chromosomes.

Note:
The result of subtle differences leads to genetic variation in our DNA and genetic variation is important for evolution which gets passed from one generation to the next and the favorable characteristics are selected for survival which gets passed to the other generation.