Biosphere Contents

2. Diversity

Sexual reproduction occurs via the fusion of male and female gametes

Tortoises mating

Sexual reproduction involves the production of two different types of gametes (tiny sperm and much larger eggs), which fuse. The fertilised eggs (zygotes) then grow by repeated cell division, also undergoing differentiation (cell specialisation) to form new multicellular organisms. The gametes are produced in specialised tissues, which are often borne on separate individuals, resulting in distinct males and females. In plants, both male and female organs are typically found on the same individuals, while in animals they occur more often as separate sexes.

What is the key characteristic of sexual reproduction?