NEET BIOLOGY

Detailed explanation-1: -Crossing over is a cellular process that happens during meiosis when chromosomes of the same type are lined up. When two chromosomes-one from the mother and one from the father-line up, parts of the chromosome can be switched. The two chromosomes contain the same genes, but may have different forms of the genes.

Detailed explanation-2: -During metaphase of meiosis I, synapsed pairs of homologous chromosomes (known as bivalents or tetrads) are lined up on an imaginary plane in the middle of the cell called the metaphase plate. The chromosomes are attached to spindle fibres at their centromeres.

Detailed explanation-3: -During meiosis, homologous chromosomes (1 from each parent) pair along their lengths. The chromosomes cross over at points called chiasma. At each chiasma, the chromosomes break and rejoin, trading some of their genes. This recombination results in genetic variation.

Detailed explanation-4: -Answer and Explanation: Meiosis is another type of cell division that occurs during gamete formation. It gives rise to genetic variation due to independent assortment and crossing over.