A: The corneal reflex is an involuntary closing of the eyelids when the cornea is touched by a foreign object. The function of this reflex is to protect the eye from damage. Absence of a corneal reflex may indicate damage to the fifth and seventh cranial nerves, which mediate the reflex.
Cellular respiration is the process by which the chemical energy of food molecules is released and partially captured in the form of ATP. Carbohydrates, fats, and proteins can all be used as fuels in cellular respiration, but glucose is most commonly used as an example to examine the reactions and pathways involved.
Photosynthesis uses water, sunlight, and carbon dioxide from the atmosphere to create glucose molecules, and releases oxygen as a by-product. Cellular respiration uses glucose molecules and oxygen to produce ATP molecules and carbon dioxide as the by-product. Photosynthesis takes place only when there is sunlight. Cellular respiration occurs at all times. Photosynthesis involves conversion of one type of energy into another: light energy into chemical energy. Cellular respiration involves using that chemical energy and breaking it down to release energy.