Video Transcript
Which of the following best defines
metabolism? (A) Metabolism is the total energy
input divided by the total energy output of an organism. (B) Metabolism is the sum of the
chemical reactions that occur in each cell of an organism. (C) Metabolism is the sum of all
the energy lost from an organism. (D) Metabolism is how quickly the
body digests a meal. (E) Metabolism is how quickly a
person can lose weight.
This question is asking us about
metabolism, which refers to all the chemical reactions that occur within the
body. There are two types of metabolic
reactions: catabolic and anabolic. Catabolic reactions are reactions
that break down large molecules into smaller units to release energy. Anabolic reactions, on the other
hand, are the reverse set of reactions where small molecules can be assembled into
larger molecules. These reactions involve energy, and
this comes from the energy that was released from the catabolic reactions.
Now that we’ve discussed
metabolism, let’s go through our answer choices to choose the best definition. Answer choice (A) is incorrect
because this is describing a type of formula for how efficient the body is in using
energy and is not describing metabolism. Answer choice (B) seems to be
correct because metabolism represents all the chemical reactions that are occurring
within the body. But before making our final
decision, let’s look at the remaining options.
Answer choice (C) is incorrect
because metabolism isn’t the sum of the lost energy in an organism. Answer choice (D) is also
incorrect. Although metabolism does affect how
quickly a meal is digested, this itself isn’t the correct definition. Answer choice (E) is incorrect. Again, metabolism does affect how
quickly a person can lose weight, but this isn’t the correct definition. Therefore, the option that best
defines metabolism is given by answer choice (B). Metabolism is the sum of the
chemical reactions that occur in each cell of an organism.
