Other Free Encyclopedias » 21st Century Webster's Family Encyclopedia » 21st Century Webster's Family Encyclopedia - Bell's palsy to Black Friday

Biological clock

rhythms circadian activities cycle

Biological clock, mechanism that controls the rhythm of various activities of plants and animals. Some activities, such as mating, migration, and hibernation, have a yearly cycle; others, chiefly reproductive functions (including human menstruation), follow the lunar month. But the majority have a period of roughly 24 hours, called the circadian rhythm. Although related to the day/night cycle, circadian rhythms are not directly controlled by it. Many organisms in unvarying environments will continue to show 24-hour rhythms, but the pattern can be changed and the clock “reset.” In December 1997 a human clock gene “rigui” was discovered, named after the ancient Chinese sundial.

Biological warfare [next] [back] Biogenesis

User Comments

Your email address will be altered so spam harvesting bots can't read it easily.
Hide my email completely instead?

Cancel or