Well, the cell would be out of energy! The mitochondria plays a very important role in cell functions. With out it, it cannot do whatever job that needs to be acquired.
The reactions release chemical energy that the cells can use to power growth and other important cell processes
Striking a matchstick as after it strikes it gives off both heat and light.
Yes, since B and C will be pushing towards each other, it will form a mountain.
I believe this would be the cerebellum. This part of the brain is used for motor control like moving the fingers say and cognitive functions (to do with thinking) and also can affect the feelings of pain and pleasure.