In a general sense reproduction is one of the most important concepts in biology: it means

making a copy, a likeness, and thereby providing for the continued existence of species.

Although reproduction is often considered solely in terms of the production of offspring in

animals and plants, the more general meaning has far greater significance to living organisms.

To appreciate this fact, the origin of life and the evolution of organisms must be considered.

One of the first characteristics of life that emerged in primeval times must have been the ability

of some primitive chemical system to make copies of itself.

At its lowest level, therefore, reproduction is chemical replication. As evolution progressed, cells

of successively higher levels of complexity must have arisen, and it was absolutely essential

that they had the ability to make likenesses of themselves. In unicellular organisms, the ability

of one cell to reproduce itself means the reproduction of a new individual; in multicellular

organisms, however, it means growth and regeneration. Multicellular organisms also reproduce

organisms, however, it means growth and regeneration. Multicellular organisms also reproduce

forms have a large egg and a minute sperm (oogamy). The sperm are usually motile and the

The double helices duplicate themselves by separating at one place between the two strands

overpopulation and disease). The numbers of some organisms fluctuate cyclically but always

he failed to fathom the mechanism of heredity. Moreover, the amount of variation is particularly

offspring--but they do so in a variety of ways, many involving complex organs and elaborate

Some common words found in the essay are:
ENCYCLOPÆDIA BRITANNICA, Charles Darwin, DNA RNA, natural selection, gametes produced, life cycle, multicellular organisms, cell reproduction, sexual reproduction, female gametes produced, male female gametes, messenger rna, unicellular organisms, dna molecules, multicellular organisms reproduce, dna rna, examples forms separate, extreme examples forms,
Approximate Word count = 4058
Approximate Pages = 16 (250 words per page double spaced)