How does regular exercise make us more alert and energetic?
a. it gets our hearts beating faster and gives us a rush of energy.
b. exercise increases our endurance and therefore we feel less tired.
c. during exercise the brain releases endorphins, the chemicals that improve our mood.
d. we breathe in more oxygen while exercising, which us feel more awake.

Which statement best illustrates that problem solving can create new medical devices? robert hooke was in charge of verifying the information that was sent to the royal academy. william harvey did experiments with apes to learn about the circulatory system. the stethoscope was invented because the physician did not want to put his head on women's chests to listen to their heart and lungs. anton van leeuwenhoek was a very curious man and looked at just about everything under this microscope.