1. Break down of Food into Energy 
Oxygen
2. Absorb X - Rays in Bones Calcium
3. Cell Membrane Function Sodium
4. All Organic Compounds Carbon
we know automatically that glucose and pyruvate are wrong answers due to the fact that glucose is sugar and that pyruvate is a type of acid. this just leaves us with ADP and ATP now ADP and ATP are very close answers, since ADP is what makes ATP, but an electron transport change usually involves the transfer of electrons well if we look at their chemical formulas, we can see that ATP has more 1 more oxygen than ADP, and this kind of chain usually adds additional oxygen which gives us ATP as our answer.
Deep inside the core of the sun, protons can collide into eachother with enough speed that they stick together to form a helium nucleus and generate a big amount of energy at the same time.
Maintenance of normal sinus rhythm
antidysrhytmic drugs are used to treat abnormal rhythm of the heart. Abnormal rhythm is usually due to the irregular electrical stimulation of the electrical activity of the heart. This can work by correcting the cardiac function there are four classes of this drugs such as Class I for sodium channels, Class II which are the beta blocker, Class III which are the drugs that prolong repolarization and Class IV which are the calcium channel blocker.
Endothermic reactions are chemical reactions that absorb more energy than they release.
