NEET BIOLOGY

Detailed explanation-1: -In meiosis, a single cell divides twice to produce four daughter cells. These daughter cells or sex cells have exactly half the genetic material of normal gametes. Meiosis necessitates two divisions since it produces a haploid cell with half the amount of chromosomes. Thus meiosis occurs twice.

Detailed explanation-2: -Because the chromosome number of a species remains the same from one generation to the next, the chromosome number of germ cells must be reduced by half during meiosis. To accomplish this feat, meiosis, unlike mitosis, involves a single round of DNA replication followed by two rounds of cell division (Figure 1).

Detailed explanation-3: -From Amy: Q1 = Cells undergoing mitosis just divide once because they are forming two new genetically identical cells where as in meiosis cells require two sets of divisions because they need to make the cell a haploid cell which only has half of the total number of chromosomes.

Detailed explanation-4: -Although the nucleus divides twice during meiosis, the DNA is replicated only once. Unlike the products of mitosis, the haploid cells produced by meiosis are genetically different from one another and from the parent cell.

Detailed explanation-5: -Cells divide twice during meiosis. Before meiosis begins, the chromosomes of the parent cell are copied. A cell that is ready to divide contains two copies of each chromosome pair-twice as many chromosomes as usual. So to end up with cells that have half the usual number of chromosomes, there must be two divisions.