Studies of healthy people indicate that functioning of the human body remains essentially constant until a. after age 70. b. after age 60. c. after age 50. d. age 40.

If water were a non polar molecule, how would its properties be different ? a.) water would be a much lighter molecule b.) water would be able to climb up inside plants c.)water would not be able to form hydrogen bonds d.) water would stick together much more strongly

Where do the respiratory and circulatory systems meet? a. in the heart b. in the muscles c. in the lungs d. in the brain

When does the circulatory system work with the respiratory system? a. during blood cell formation b. during cellular respiration c. during intestinal digestion d. during a viral infection