Which product of cellular respiration is used by the human body for energy?
(a)oxygen
(b)atp
(c)sunlight
(d)co2

The correct answer is B - ATP

Cellular respiration is the process by which cell produce energy in form of ATP for functioning.

It occurs in three stages :

1. Glycolysis - takes place in the cytoplasm where a molecule of glucose is broken down to form pyruvate.

2. Krebs cycle - takes place in the mitochondria in which co -enzymes NADH and FADH are produced, and some ATP molecules.

3. Electron transport chain - takes place in the mitochondria  in which the highest number of ATP molecules, at least 34, are generated. 

when you breathe in, or inhale, your diaphragm contracts (tightens) and moves downward. this increases the space in your chest cavity, into which your lungs expand. the intercostal muscles between your ribs also enlarge the chest cavity. they contract to pull your rib cage both upward and outward when you inhale.