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.
