Question Video: Identifying the Role of Enzymes in the Digestion Process Biology

Which of the following best explains how enzymes aid digestion? [A] Enzymes release energy to aid physical processes of digestion, such as chewing. [B] Enzymes slow the rate of digestion so it does not require too much energy. [C] Enzymes regulate the pH of the digestive system to ensure it remains at optimum. [D] Enzymes break down large, complex food molecules into smaller ones that can be absorbed. [E] Enzymes are released by the gall bladder to neutralize stomach acids.

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Video Transcript

Which of the following best explains how enzymes aid digestion? (A) Enzymes release energy to aid physical processes of digestion such as chewing. (B) Enzymes slow the rate of digestion so it does not require too much energy. (C) Enzymes regulate the pH of the digestive system to ensure it remains at optimum. (D) Enzymes break down large, complex food molecules into smaller ones that can be absorbed. (E) Enzymes are released by the gall bladder to neutralize stomach acids.

Key knowledge required to select the correct option includes a general understanding of enzyme action and, more specifically, how enzymes aid in the digestion of nutrients. We’ll start with the definitions of these two key terms, enzyme — enzymes are biological molecules that speed up chemical reactions — and digestion — which is the breakdown of food into smaller particles that can be absorbed.

So how are chemical reactions related to food? Well, life, which takes place in in between cells, is largely a complex and organized system of chemical reactions that utilize nutrients and matter for energy. So we eat and digest food so we can keep our sustaining chemical reactions underway. Those nutrients include large molecules such as carbohydrates, proteins, and lipids. We need these nutrients to be transported into our cells, but for that to happen, these larger molecules, which are made out of similar repeating subunits, have to be broken down into the smaller monomer subunits so they can be transported across the cell membranes. And that’s the job of the digestive enzymes.

Carbohydrases breakdown larger carbohydrates into their smaller monomer units called sugars. Proteases break down proteins into their smaller monomer units, which are called amino acids. And lipases break down fats into glycerol and their fatty acids. Now these nutrients can be transported from the inside of the small intestine into the bloodstream and to the cells.

And we’re ready to review the solution options to our question. Option (A) says, enzymes release energy to aid physical processes of digestion such as chewing. There are a couple problems with option (A). First of all, enzymes do not release energy. They reduce the amount of energy needed for a chemical reaction to occur. And that’s another problem. Enzymes don’t help with physical processes. They help with chemical reactions.

Option (B) says, enzymes slow the rate of digestion so it does not require too much energy. But that’s the opposite of what we were just saying. Enzymes speed up chemical reactions, and those are involved in digestion. They definitely aren’t there to slow things down.

Option (C) states, enzymes regulate the pH of the digestive system to ensure it remains at optimum. pH is important for enzymes they only function within a certain range. But as we’ve said before, this isn’t the job of enzymes. That’s to speed up the chemical reactions involved in digestion.

Option (D) says, enzymes break down large, complex food molecules into smaller ones that can be absorbed. And that’s just what we’ve been talking about. So option (D) is looking pretty good.

Option (E) says, enzymes are released by the gall bladder to neutralize stomach acids. But there’s a couple problems here. First of all, the gall bladder releases bile. And enzymes do not neutralize stomach acids. They speed up the chemical reactions of digestion.

Therefore, the correct answer to this question, which of the following best explains how enzymes aid digestion, is enzymes break down large, complex food molecules into smaller ones that can be absorbed.

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