Video Transcript
What cellular process in the body
breaks down glucose to release energy? (A) Photosynthesis, (B) mitosis,
(C) synthesis, (D) respiration, or (E) breathing?
This question is asking about the
name of the process which releases energy from glucose. To make sure we can answer this
question, let’s recap about what glucose is, how we get it, and what its role is in
our bodies. Glucose belongs to the group of
monosaccharides, which are the basic building block of all carbohydrates. Mono- means one, and saccharides
refers to sugars. Carbohydrates are made up of the
elements carbon, hydrogen, and oxygen. Their main role in the body is as a
source of ready energy. But where do we get them from?
We are heterotrophs, which means we
have to consume our food. Hetero- means other, and -troph
means food. Plants, on the other hand, are
autotrophs, auto- meaning oneself, which means that they make their own food. To do this, they carry out a
process called photosynthesis. Photo- means light, and synthesis
means to make. They combine carbon dioxide and
water using sunlight as an energy source to make glucose. This process occurs in the
chloroplasts, which contain the green pigment chlorophyll to absorb the light
energy. Photosynthesis is therefore the
making of glucose in plants, not the breakdown of it in our bodies. And seeming as synthesis means to
make something, we can rule out options (A) and (C) from the possible answers.
Plants are the start of most food
chains, seeming as they make their own food. We then eat the plants or other
organisms in food chains, but what happens when we do this? The food is digested into small
soluble food molecules that enter our bloodstream. Larger carbohydrates, for example,
are broken up into their component monosaccharides, which includes glucose. The blood carries these nutrients,
such as glucose, as well as other molecules, such as oxygen, around our body and
delivers them to our cells. Wastes diffuse from the cells into
the blood and are carried away. The oxygen gets into our blood by
diffusing from the lungs. Breathing is the process of moving
air into and out of our lungs. This enables oxygen to enter our
lungs for this diffusion to happen. This means that option (E) can also
be ruled out.
But why is this oxygen needed? The oxygen is needed for a type of
cellular respiration called aerobic respiration. Aerobic respiration is the process
by which carbon-containing compounds, usually glucose, are broken down to release
energy in the form of ATP, in the presence of oxygen. This energy is used by the cells to
carry out many different functions, such as muscle contraction, metabolism, and the
formation of new cellular components.
Now that we have reviewed some of
the key facts about glucose and its role in the body, let us return to the
question. We are now left with the two
options (B) and (D). Mitosis is a type of cell division
and is not involved in energy release. We have, however, just discussed
aerobic respiration, so we now know the correct answer is (D). The cellular process that breaks
down glucose to release energy is respiration.
