Question 1
________, a hormone involved in the regulation of circadian rhythms, is secreted by the pineal gland.
◦ Serotonin
◦ Testosterone
◦ Estrogen
◦ Melatonin
Question 2
A biological cycle, or rhythm, that is approximately 24 hours long is called a(n) ________ cycle.
◦ infradian
◦ circadian
◦ diurnal
◦ ultradian