Video Transcript
The diagram provided shows the
basic structure of a plant cell, with the key organelles labeled. Which of the following is a major
function of the vacuole in a plant cell? (A) To provide the site for aerobic
respiration. (B) To provide the site for protein
synthesis. (C) To support the cell turgidity
and store nutrients. Or (D) to selectively allow
substances to move in and out of the plant cell.
The presence of a large, central
vacuole is a defining feature of plant cells and serves as the main storage
organelle. The solution inside the vacuole is
known as cell sap. It is a mix of water and other
substances, which vary depending upon the plant species and the type of plant cell
containing the vacuole. These other substances can include
salts, minerals, proteins and other nutrients, pigments, and even waste
products.
When a vacuole is full of water, it
pushes the cell contents outwards. This serves two important
purposes. First, it maintains a state of
turgidity by applying pressure to the inside of the flexible cell surface
membrane. The membrane expands into the
spaces of the rigid cell wall, giving the cell its shape and rigidity. Second, the outward pressure
applied by the vacuole pushes the chloroplasts toward the surface of the cell so
they can better access sunlight for photosynthesis.
Although our question asks about
the role of the vacuole in plant cells, this is a good time to note that animal
cells also have vacuoles. However, animal cell vacuoles are
larger in number but smaller in size. They are typically involved in
metabolic or cellular transport processes.
Now, let’s take a look at our
answer options. You may remember learning that
organelles called mitochondria are the site of aerobic respiration, so we can rule
out choice (A). The site of protein synthesis is
usually considered to be the ribosomes, and the vacuole is not involved in protein
synthesis. So, we can eliminate answer
(B). Answer choice (C) refers to an
organelle that supports cell turgidity and stores nutrients. This lines up with what we learned
about the roles of plant vacuoles, but just to be sure this is the best answer,
let’s check the remaining option.
Option (D) refers to a structure
that selectively allows substances in and out of plant cells. This describes the role of the cell
wall and cell surface membrane, not the vacuole. So, we can confirm that the correct
answer is option (C). The major functions of the vacuole
in a plant cell are to support cell turgidity and store nutrients.
