In certain organisms, like humans, there are two morphologically distinct types of gametes: (1) the male gamete (i.e. sperm cell) and (2) the female gamete (i.e. ovum). The male gamete is smaller in size and motile whereas the female gamete is several times bigger and non-motile. The haploid condition of the two gametes is essential so that at fertilization during sexual reproduction the integrity of the chromosomal number is maintained throughout generations.
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