NEET BIOLOGY

Detailed explanation-1: -Natural selection can only occur if there is variation among members of the same species. WHY? Variation in a population results from mutation and the recombination of alleles during meiosis and fertilization.

Detailed explanation-2: -Without genetic variation, a population cannot evolve in response to changing environmental variables and, as a result, may face an increased risk of extinction. For example, if a population is exposed to a new disease, selection will act on genes for resistance to the disease if they exist in the population.

Detailed explanation-3: -Only when variation among organisms is inherited from the previous generation, i.e. it has a genetic basis, will natural selection be able to occur. Natural selection cannot act on variation that is due purely to environmental conditions.

Detailed explanation-4: -Genetic variations that alter gene activity or protein function can introduce different traits in an organism. If a trait is advantageous and helps the individual survive and reproduce, the genetic variation is more likely to be passed to the next generation (a process known as natural selection).

Detailed explanation-5: -Genetic variation is essential for natural selection because natural selection can only increase or decrease frequency of alleles that already exist in the population. Genetic variation is caused by: mutation.