13 Pepsin is a protein which is produced in the stomach and is one of the main digestive enzymes found in many animals. This enzyme breaks down proteins found in food into smaller peptides. Chymotrypsin and
trypsin are also enzymes and play a similar role as pepsin in the digestive system. What is the primary
role of all digestive enzymes?
A) Increase the amount of energy needed to digest food
B) Ensure that waste products are quickly removed
C) Speed up chemical reactions involved in nutrient breakdown
D) Fight off any pathogens found in the body

the aswer is letter c

the answer is b: 1.4 km/hr

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.