Which processes lead to most genetic variation in sexually reproducing organisms?
A: Independent assortment of chromosomes in Meiosis.
B: Crossing over.
C: Random fertilization.
D: A, B, and C are correct.
The correct answer is option D. Options A, B and C all are true.
The processes which lead to genetic variation in sexually reproducing organisms include; a) Independent assortment of chromosomes in Meiosis, b) crossing over, and c) random fertilization.
Let’s first discuss “what is genetic variation?” before mentioning the processes which introduce the genetic variation.
Genetic variation is the process which has a crucial role in the process of natural selection by enabling the best individuals to reproduce and survive.
Genetic variation occurs in the processes of crossing over and independent assortment during the phase of Meiosis in the gametes or sex cells.
A: Independent assortment of chromosomes in Meiosis:
Independent Assortment shows how different genes separate from one another independently when reproductive cells develop. This independent assortment of genes occurs during Meiosis.
Meiosis is the process of cell division that happens in the gametes or sex cells during sexual reproduction. Meiosis ensures the introduction of genetic variation.
In Meiosis, the cell divides twice in such a way that four cells are formed from one parent cell. The chromosomes also exchange their genetic material in crossing over.
As the chromosomes vary from one other so, they randomly line up in the cell. It is called independent assortment.
B: Crossing over:
The process in which the chromosomes exchange their genetic material is called crossing over.
Crossing over occurs during “Prophase I,” which is the first stage of Meiosis. During this stage, the homologous chromosomes pair up.
When homologous chromosomes exchange segments with each other, it switches the pieces of DNA as (Chromosomes contain genes in the form of DNA sequences); thus, variation occurs.
During the process of crossing over the chromosomes break as well as rejoin at the same place.
C: Random Fertilization:
Random fertilization is another process that leads to Genetic Variation. Thus, sexual reproduction ensures that genetic variation happens during cell division and fertilization.