Which of the following is true of the transverse section of a dicot stem?

Analyze the question: We need the true statement about the transverse section (T.S.) of a dicot stem, from the structure as seen under the microscope.

Concept: Structure of a dicot stem (outside to inside)

1. Epidermis, the outermost protective layer
2. Cortex, made of collenchyma and parenchyma
3. Vascular bundles, arranged in a ring
4. Pith, the central region of parenchyma

Each vascular bundle is open and has this order from outside to inside:

• Phloem (outer)
• Cambium (middle)
• Xylem (inner)

Check each option:

• A. The xylem is more interiorly located than the phloem. True. In each bundle, the xylem faces the pith (inside) and the phloem faces the cortex (outside).
• B. The cambium lies between the cortex and the vascular bundles. False. The cambium lies within each vascular bundle, between the xylem and phloem, not outside the bundles.
• C. The vascular bundles are randomly scattered within the cortex. False. Scattered bundles are a feature of the monocot stem. Dicot bundles are in a ring, and they lie inside the cortex, not scattered within it.
• D. The epidermis is completely encircled by the cortex. False. The epidermis is the outermost layer and encircles the cortex, not the other way round.

**Answer: A.

Exam tip: Remember "Dicot = Direct ring, Monocot = Many scattered." For the bundle order, think "Xylem is eXit toward the centre": xylem inside, phloem outside, with cambium sandwiched between them in dicots.