The organism which are reproduced by asexual mode of reproduction are exact copy of themselves while the organism which are reproduced by sexual mode of reproduction are not exact copy of the organism.This all happens because of variation.
Every single life starts with a basic unit called the cell. The cell contains a\xa0nucleus, which carries the genetic information for the next generation in the form of DNA (DeoxyriboNucleic Acid). We can say that the fundamental process of reproduction is DNA replication. When a reproducing cell commences division, it primarily starts to make a replica of its DNA. This replica will be separated from the original DNA. Since a DNA can’t build up an organism all by itself, the cell also divides into two. We get a cell with new DNA. According to the DNA codes, the proteins are made in the new cell. Accordingly, the cell evolves as a new individual which looks similar to the original cell. These two cells might look similar in their body designs and physiology, but they are not identical.At the time of formation of gametes, meiosis occurs. Eventually, this creates a DNA different from the parent cell due to crossing over and recombination. A change in the information on DNA implies it is the initiation of variation. Altered DNA copy will code for the proteins different from the original one. Different proteins lead to variation in the organism. The body designs that an organism inherited from its parent will not be considered anymore. This variation might be drastic or slow. Variation during reproduction is an inbuilt tendency and it lays a pathway for\xa0evolution.In an asexually reproducing organism, variation is limited. Organisms create exact copies of themselves, a clone. But the chances of variation are very high in a sexually reproducing organism.