Video Transcript
Which of the following is a polymer
found in the cell walls of vascular tissue, such as the xylem, to provide additional
structural support? (A) Lignin, (B) lactose, (C)
glycogen, (D) collagen, or (E) keratin.
To answer this question, let’s look
at the cell walls of vascular tissue in plants in more detail. While animals like you and I have a
skeleton to provide support, plants do not. And so they use other mechanisms to
provide structural support. Structural support is often
achieved by depositing hard polymers in the cell walls of certain parts of the
plant. In addition to structural support,
these polymers often provide a waterproof or impermeable barrier.
But which polymer is deposited in
the cell wall of vascular tissue? In vascular tissue, such as the
xylem, lignin is the substance deposited into the cell walls where it has several
roles. Firstly, lignin provides additional
structural support to the xylem by making its vessels more rigid, which helps to
keep the plant upright. Secondly, it helps to make the cell
walls waterproof, which is especially important in the xylem as it is responsible
for transporting water and mineral ions from the roots to the rest of the plant. The lignin increases the efficiency
of this water transport system by preventing water from leaking out of the xylem
vessels.
Now we have enough information
about structural support in the vascular tissues of a plant to answer the
question. The polymer found in the cell walls
of vascular tissue, such as the xylem, which provides additional structural support
is (A), lignin.
