CBSE
Class 10
Class 12
Reproduction helps in maintaining a proper balance among various biotic constituents of the ecosystem. Moreover, reproduction also facilitates evolution because variations come through reproduction; over several generations.
Organisms look similar because their body designs are similar. the chromosomes in the nucleus of a cell contain information for the inheritance of features from parents to next generation in the form of DNA (Deoxyribo Nucleic Acid) molecules. The DNA in the cell nucleus is the information source for making proteins.
DNA replicates and forms new cells causing variation. So, these new cells will be similar but may not be identical to the original cell.
Variations allow organisms to exist in diverse habitats or niches. In the absence of variations, a species may be restricted to the particular area. If this area gets drastically altered, due to various natural or man-made causes, the species may be wiped out. However, if some variations were present in a few individuals, these colonize other habitats and could survive. But if variations are present in a single organism there would be very little for it to survive.