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There are basically two types of reproduction - asexual and sexual. This classification is based on the number of parents.
Asexual reproduction involves only one parent and the offspring is genetically similar to the parent.
Sexual reproduction involves two parents and the offspring has a fusion of the characteristics of both the parents.
Before proceeding further, let us recollect what we know about the genetic material and its division.
All organisms are made up of cells. The cells are of two types:
Vegetative cells are those that are present everywhere in the body of the organism whereas reproductive cells are those that are present in the reproductive structures and are associated with sexual reproduction.
Each cell has a nucleus that contains the genetic material. This is in the form of a chemical substance called the DNA in most organisms. The genetic material is arranged in the form of thread-like structures called the chromosomes. On the chromosomes are present the genes that give the chromosomes a beaded appearance. The chromosomes are present in pairs. If one chromosome is taken from each pair it forms a haploid set. The full complement of chromosomes is called a diploid set. All the genes together have all the information needed to make up an organism and regulate its functioning.
The vegetative cells only show mitotic division where the number of chromosomes in every division remains the same. However, the reproductive cells show mitotic and meiotic division. Mitotic division increases the number of cells and meiotic division results in the formation of gametes that have only half the number of chromosomes (haploid). Each mitotic division results in two daughter cells whereas meiotic division results in four daughter cells that are called gametes.
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