Video Transcript
Which of the following is not a use
of ATP in animals? (A) Synthesis of large molecules
from smaller ones. (B) Movement and locomotion. (C) Regulation of body
temperature. (D) Simple diffusion of substances
across cell membranes. Or (E) active transport of
substances across cell membranes.
ATP is the molecule that carries
energy in animal cells. It provides the energy required for
countless processes within the cell. All of the answers here are
processes that occur in animal cells. So which require energy, and
therefore ATP, to complete? Let’s take a look at the answers
and narrow down our options.
Synthesizing large molecules from
smaller ones does require energy because bonds, which carry energy, are being
built. This is called anabolic metabolism,
and it occurs when smaller molecules, such as amino acids, are joined together. With the use of ATP, bonds are
built between the amino acids, which create a larger molecule, known as a
protein. Since this process does use ATP, we
can eliminate it.
Movement and locomotion require
energy as well. We know our bodies require more ATP
when we are active because we breathe faster and our hearts beat at a faster
rate. This is because within our cells,
cellular respiration is occurring at an increased rate to match the cells demand for
ATP. As a result, our body is working
overtime to get oxygen to the cells and carry waste carbon dioxide away from those
cells to allow cellular respiration to continue to occur. So since we know that movement
requires energy, we can eliminate answer (B) as well.
Energy can be required for the
regulation of body temperature as well, for example, when we move or shiver in order
to keep our body warm. So answer (C) would not be the best
choice either.
Now let’s discuss answers (D) and
(E), which are about transport across membranes. This is an important process by
which nutrients, vitamins, and chemicals pass into and out of cells. Molecules will naturally move from
areas of high concentration to areas of low concentration with no input of
energy. This process is known as
diffusion. When something must be transported
against the concentration gradient, meaning from areas of low concentration to areas
of high concentration, this requires active transport, which uses energy. Answer (E) describes active
transport, which is a process that does require energy in the form of ATP. So we can eliminate that
choice.
Answer (D) describes diffusion,
which is a passive process that does not use energy or, specifically, ATP. Therefore, the correct answer is
(D). Simple diffusion of substances
across cell membranes is not a use of ATP in animals.