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The Growth Of Populations: The problem of human growth—the population explosion—must be understood in the same context as the growth of populations of other organisms. At present the human population is in a growth phase with a mean doubling time of about 25 years. Although the number of humans an double every 25 years, the food supply cannot Jo so indefinitely.
The properties of the growth phase described for microorganisms also applies to the growth of populations of higher organisms. In a situation where food and space were virtually unlimited, a population of animals or plants would double (or triple or quadruple) at a constant rate just as bacteria do, and the resulting increase would be just as devastating, although it would take a few years instead of a few days.
Growth Phase. Three basic factors affect the growth phase of cell populations: (1) the number of organisms involved—the more parent organisms present, the more offspring there can be. (2) During this period most of the organisms reproduce; few are barren. (3) The generation time is constant—that is, the time it takes for each organism to appear, mature, and reproduce is relatively constant throughout the growth period.
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