The brain... for most people.
The estrous cycle of pigs is 21 days. Humans have a menstrual cycle which can last from 21-35 days.
A cat ages seven times faster in relation to humans, so yes, a 3-year-old cat is equivalent to a 21-year-old human.
About 21 ounces.
21 goats left
14 days I think
Hmm, internal? I think there are 21 or 22 internal organs.
21
The estrous cycle of pigs is 21 days. Humans have a menstrual cycle which can last from 21-35 days.
21%
21
Dinosaurs - 1991 Charlene and Her Amazing Humans 3-21 was released on: USA: 9 May 1993
Trisomy 21, Down's syndrome
Trisomy 21, Down's syndrome, is viable.
Psychic Investigators - 2006 Southern Organs Case 1-7 was released on: USA: 21 April 2006
48 Hours - 1988 Live to Tell Hunting Humans 24-21 was released on: USA: 26 March 2011
Yes. The air is 21% oxygen which is what humans run on. It is 79% nitrogen which we filter out. I learned this today in Health class.
In humans, the kidneys are two small organs located near the vertebral column at the small of the back. The left kidney lies a little higher than the right kidney. They are bean-shaped, about 4 in. (10 cm) long and about 21/2 in. (6.4 cm) wide.