During its development, a tracheid elongates in a direction parallel to the shoot or root axis. Based on this information, what can you say about the orientation of cell-wall cellulose microfibrils and cytoplasmic microtubules in the developing tracheid?
a. The microfibrils will be oriented perpendicularly (at right angles) to the long axis of the developing tracheid, encircling it, but the cytoplasmic microtubules will be oriented parallel to the direction in which the tracheid is elongating.
b. Microfibrils and microtubules will both be oriented perpendicularly (at right angles) to the elongating axis of the tracheid.
c. Microfibrils and microtubules will both be oriented parallel to the direction of tracheid elongation.
d. Microfibrils will be oriented parallel to the direction of tracheid elongation, but microtubules will be perpendicular (at right angles) to both the microfibrils and the elongating tracheid.
e. None of the above is correct.
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BIOLOGY
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