The average sperm count in the developed world has fallen by one third over the last 15 years.
The present average sperm count is 30 million/cm of semen.
Calculate the average yearly fall in sperm production over the 15 year period.

Which statement describes a way in which the digestive and excretory systems work together? a. the nephrons absorb nutrients from food going to the large intestine. b. the excretory system balances blood gases in the small intestine. c. the intestinal villi filter blood and send wastes to the bladder. d. the excretory system balances the salts and water obtained from digested food