Basic Features of Reproduction
1. Cell Division
A key event which occurs during reproduction is cell division. In the previous classes you have studied two types of cell division ie., mitosis and meiosis. Mitosis is a division in which replicated chromosomes equally distributed into two daughter nuclei so that the daughter cells have same number and type of chromosomes as present in the parent cell. It is therefore.called equational division. However, in meiosis daughter cells formed have half the number of chromosomes as compared to the parent cell. So it is a reductional division. Crossing over occurs during this division. It introduces new combinations of genes or recombinations which result in variations ie., degree of differences amongst the progeny and between the progeny and the parent.
2. Duplication of Cellular Apparatus
Before a cell divides, all the cellular apparatus must be duplicated so that cellular material present in parent cell can be equally distributed amongst two daughter cells. It involves replication of chromosomes in the nucleus of a cell which contain information for inheritance of features from parents to next generation in the fom of DNA and involves formation of RNA, proteins and other biochemicals.
3. Formation of Reproductive Units
Reproductive units are specialised or non-specialised parts of an organism which after separation or modification results in the formation of new individuall/offsprings.