When energy changes form, some energy is added as heat gained given off as heat returned to its source

Given off

Explanation:

Energy is neither created nor destroyed it can only be converted from one form to another form. But all the energy is not converted from one form to another some of the energy is radiated in the form of heat.

The energy from the system is released in the form of heat. Heat is not used when form is changed. Energy is released in the form of heat.

hence, the correct answer is

both anaerobic and aerobic respiration use glucose (or other carbohydrates), proteins and lipids to produce atp and nadh. cell uses those energy molecules, obtained from food and   breaks them down during the chemical reactions of respiration. in anaerobic respiration, nadh is regenerated to nad+ by enzymes lactate dehydrogenase (lactate is produced, e.g. in muscle cells) or by alcohol dehydrogenase where ethanol is produced (alcohol fermentation), while in aerobic respiration, electrons from nadh are deposited in the mitochondria to regenerate nad+ (electron transport chain. anaerobic respiration produces 2 atp per molecule of glucose compared to aerobic respiration where about 38 atp molecules are produced.

multiply it by 5 in order for you to understand i cant give an exact answer.