Video Transcript
Cellulose is a polysaccharide found in plant cells. What is the primary role of cellulose in plant cells? (A) Cellulose is the main component of plant cell walls that provides rigidity and
structure for the cell. (B) Cellulose is broken down in cellular respiration to release energy. (C) Cellulose is the main component of ribosomes within the cell that help synthesize
proteins. Or (D) cellulose is the pigment contained within plant cells that captures the
sunlight needed for photosynthesis.
This question asks us about the primary role of cellulose in plant cells. You may have previously learned that a major difference between plant and animal
cells is that plant cells have cell walls outside of their cell surface membranes,
while animal cells do not. In plants, the cell wall is made of cellulose, which is a polysaccharide composed of
𝛽 glucose monomers.
𝛽 glucose molecules bond in an alternating fashion, as shown in the diagram, forming
long, rigid, unbranched chains. These chains readily form hydrogen bonds with each other, leading to larger, stacked
structures. This molecular arrangement gives cellulose its incredible strength, comparable to
that of steel. And its strength and rigidity make it well suited for its primary role of providing
structural integrity to the plant cell walls.
Plant cell walls also have many secondary functions that are facilitated by
cellulose, for example, helping to prevent water loss, keeping cells from bursting
under turgor pressure created by excess water, and protecting the cell from
pathogens.
Now that we know a little bit about cellulose and plant cell walls, let’s return to
our question. It asks specifically about the primary role of cellulose, which we learned was to
provide structure to plant cells. So the correct answer option is (A). Cellulose is the main component of plant cell walls that provides rigidity and
structure for the cell.
