Biological clock may refer to:
- Circadian rhythm, living organisms' adaptations to solar related rhythms
- Age and female fertility
Famous quotes containing the words biological and/or clock:
“Man’s biological weakness is the condition of human culture.”
—Erich Fromm (1900–1980)
“Stands the Church clock at ten to three?
And is there honey still for tea?”
—Rupert Brooke (1887–1915)