DNA (Deoxyribonucleic acid) is the genetic material found in the chromosomes, which are present in the nucleus of a cell. The DNA is the information site for making proteins and each specific type of protein leads to a specific type of body design.
Thus, it is the DNA molecule that determines the body design of an individual. Therefore, it can be concluded that it is the DNA that gets transferred from parents to offsprings and makes them look similar.
Variations are beneficial to the species than individual because sometimes for a species, the environmental conditions change so drastically that their survival becomes difficult.
For example, if the temperature of water increases suddenly, then most of the bacteria living in that water would die. Only few variants that are resistant to heat would be able to survive. However, if these variants were not there, then the entire species of bacteria would have been destroyed. Thus, these variants help in the survival of the species. However, all variations are not necessarily beneficial for the individual organisms.
|Binary fission||Multiple fission|
|1. Splitting of unicellular organisms like amoeba into two equal halves during cell division is termed binary fission.||1. Division of single-celled organisms such as malarial parasites into many daughter cells simultaneously is termed multiple fission.|
|2. Amoeba and Bacteriadivide by binary fission.||2. Plasmodium divide by multiple fission|
There are many advantages, if an organism reproduces through spores.
Advantages of spore formation:
Large numbers of spores are produced in one sporangium.
Spores are distributed easily by air to far-off places to avoid competition at one place.
Spores are covered by thick walls to prevent dehydration under unfavourable conditions.
Simple organisms such as Hydra and Planaria are capable of producing new individuals through the process of regeneration. The process of regeneration involves the formation of new organisms from its body parts. Simple organisms can utilize this method of reproduction as their entire body is made of similar kind of cells in which any part of their body can be formed by growth and development.
However, complex organisms have organ-system level of organization. All the organ systems of their body work together as an interconnected unit. They can regenerate their lost body parts such as skin, muscles, blood, etc. However, they cannot give rise to new individuals through regeneration.