Question

The organic food material is translocated through phloem in the stems of following

• A. Dicot stem with conjoint, collateral, closed vascular bundles
• B. Monocots stems with vascular bundles
• C. Dicot stems with conjoint, collateral, open vascular bundles
• D. Dicot stem with bicollateral vascular bundles

Hint:

Open vascular bundles = presence of cambium = secondary growth + efficient transport.

Answer 1

The Correct Option is C

Phloem is the tissue that carries manufactured food, mainly sucrose, from the leaves to the rest of the plant, and this question asks in which type of stem that transport tissue is organized around a cambium.

1. Dicot stem with conjoint, collateral, closed vascular bundles: A closed bundle has no cambium between its xylem and phloem, so it cannot add new conducting tissue over time. Real dicot stems are not built this way, which rules this option out.
2. Monocot stems with vascular bundles: Monocot stems keep their bundles closed, without cambium, and scattered through the ground tissue rather than in a ring. Their phloem still works, but the stem itself lacks the open, cambium bearing structure the question is pointing to.
3. Dicot stems with conjoint, collateral, open vascular bundles: A typical dicot stem has its bundles arranged in a ring, each one conjoint (xylem and phloem on one radius) and collateral (phloem outside, xylem inside), with a strip of cambium sitting between them. That cambium is what makes the bundle open, letting the stem thicken with age while phloem continues moving food outward.
4. Dicot stem with bicollateral vascular bundles: Bicollateral bundles carry phloem on both the inner and outer face of the xylem, a special arrangement seen in families like Cucurbitaceae and Solanaceae, not the general dicot stem this question describes.

The general, cambium bearing arrangement typical of dicot stems, where phloem actively carries organic food, is the conjoint, collateral, open type.

Let's summarize:

• Closed bundles (monocot stems): no cambium, fixed conducting tissue.
• Open bundles (typical dicot stems): cambium present between xylem and phloem, supports secondary growth.
• Bicollateral bundles are a special case limited to certain plant families.

So the answer is dicot stems with conjoint, collateral, open vascular bundles.