NEET BIOLOGY

Detailed explanation-1: -Genetic variations can arise from gene variants (also called mutations) or from a normal process in which genetic material is rearranged as a cell is getting ready to divide (known as genetic recombination). Genetic variations that alter gene activity or protein function can introduce different traits in an organism.

Detailed explanation-2: -What causes a mutation? Mutations can be caused by high-energy sources such as radiation or by chemicals in the environment. They can also appear spontaneously during the replication of DNA. Mutations generally fall into two types: point mutations and chromosomal aberrations.

Detailed explanation-3: -The ultimate source of all genetic variation is mutation. Mutation is important as the first step of evolution because it creates a new DNA sequence for a particular gene, creating a new allele. Recombination also can create a new DNA sequence (a new allele) for a specific gene through intragenic recombination.

Detailed explanation-4: -Natural selection acts upon two major sources of genetic variation: mutations and recombination of genes through sexual reproduction. Most mutations do not affect the reproductive fitness of individuals–some may be beneficial, some may be harmful, and many may be neutral.