Question

read the passage to answer the question.
have you had the chance to watch a tree grow over a span of several years? did you notice that the tree grew thicker and taller? deep in the roots of the tree and high in the growing shoots are meristem cells. each year, the meristem cells help the tree continue to grow.
as a tree ages, it needs to keep making more xylem and phloem cells to carry water and food.
which statement explains how this occurs?
the existing xylem and phloem divide to make more xylem and phloem.
xylem and phloem from one part of the plant are transferred to another part.
meristem cells divide and some of the new cells differentiate into xylem and phloem.
cell division is not necessary for a plant to create new xylem and phloem cells.

Explanation:

1. Analyze the first option: Xylem and phloem are permanent tissues and do not divide to form more of themselves, so this is incorrect.
2. Analyze the second option: Xylem and phloem are not transferred from one part to another to form new ones; they are formed by cell differentiation, so this is incorrect.
3. Analyze the third option: The passage states that meristem cells help the tree grow. Meristem cells are undifferentiated and can divide. When they divide, some of the new cells can differentiate into xylem and phloem, which matches the process of a tree making more xylem and phloem as it ages.
4. Analyze the fourth option: Cell division is necessary for the formation of new cells (including xylem and phloem), so this statement is incorrect.

Answer:

C. Meristem cells divide and some of the new cells differentiate into xylem and phloem.