True or False. Measuring heart rate allows the exerciser to determine if they are working too hard or not hard enough?

 True

Explanation:  Your heart rate measures the speed of your heart (beats per minute).  This helps measure the body's physical fitness rate.  If your physical activity increases or you are working harder to do something, then your heart rate goes up.  If your physical activity decreases or working not as hard, then your heart rate goes down.  Your heart rate can also depend on your diet and stress.  

a mother eats twice as much to support her growing fetus

limiting sugar intake in a mother with gestational diabetes, switching from diving to swimming.   depending on whether the patient is normal weight, over weight or gain will differ depending on that.

fluid balance is an aspect of the homeostasis of organisms in which the amount of water in the organism needs to be controlled, via osmoregulation and behavior, such that the concentrations of electrolytes (salts in solution) in the various body fluids are kept within healthy ranges. the core principle of fluid balance is that the amount of water lost from the body must equal the amount of water taken in.