Ans: DNA (deoxyribonucleic acid) plays a central role in heredity and evolution, serving as the molecular basis for both processes. Here’s how DNA contributes to heredity and evolution:
Heredity:
a). Inheritance of Genetic Information:
DNA carries the genetic information or instructions necessary for the development, growth, and functioning of living organisms.
Offspring inherit their DNA from their parents, receiving a combination of genetic material from both maternal and paternal sources.
During reproduction, DNA is passed from one generation to the next, ensuring the transfer of genetic traits from parents to offspring.
b). Genetic Variation:
DNA contains genes, which are segments of the DNA molecule that code for specific traits or characteristics.
Genetic variation arises from differences in the DNA sequences of genes and alleles (gene variants).
This variation is a crucial aspect of heredity because it leads to diversity among individuals within a species. It allows for adaptation to changing environments and is essential for the survival and evolution of species.
Evolution:
a). Genetic Basis of Variation:
DNA is the source of genetic diversity within populations.
Mutations, which are changes in DNA sequences, introduce new genetic variations. Mutations can be beneficial, neutral, or harmful.
Natural selection acts on these genetic variations, favoring individuals with traits that provide a survival or reproductive advantage. Over time, this can lead to the accumulation of advantageous traits in a population
b). Mechanism of Natural Selection:
DNA is central to the process of natural selection, which is a fundamental driver of evolution.
Individuals with DNA variations that confer advantages in terms of survival and reproduction are more likely to pass on their genes to the next generation.
Over successive generations, the frequency of advantageous DNA variants may increase in a population, leading to evolutionary changes.
c). Genetic Drift and Gene Flow:
DNA also plays a role in other evolutionary mechanisms, such as genetic drift (random changes in allele frequencies) and gene flow (the exchange of genes between populations).
These processes, influenced by DNA variation, can lead to divergence or convergence of populations, contributing to speciation and the formation of new species over long periods.