Q.Grafting is successful in dicots but not in monocots because the dicots have
a. Vascular bundles arranged in a ring
b. Cambium for secondary growth
c. Vessels with elements arranged end to end
d. Cork cambium

Step 1. Recall what a successful graft actually needs. Grafting works by pressing the cut surfaces of a stock and a scion together so their tissues heal into one continuous plant. What makes that union permanent and functional is new vascular tissue - specifically cambium - forming across the graft line and differentiating fresh xylem and phloem that connect the two pieces.

Step 2. Recall the dicot stem's vascular arrangement. A dicot stem's vascular bundles are open (a cambium is present between the xylem and phloem in each bundle) and arranged in a ring around the pith (the eustele), so a continuous ring of cambial tissue is available all the way around the stem's circumference to fuse across a cut.

Step 3. Recall the monocot stem's vascular arrangement. A monocot stem's vascular bundles are closed (no cambium between xylem and phloem) and lie scattered through an undifferentiated ground tissue rather than in a ring, so the stem has no cambium anywhere at all - there is simply no dividing tissue available to generate the new vascular connections a graft union needs. …

Identify that a graft union is made by dividing cambial tissue, then compare which group (dicot, with open ring-arranged bundles, vs monocot, wi …

• Picking 'vascular bundles arranged in a ring' as the answer without recognising that the ring only matters because it is a ring of cambium-bearing (open) bundles. …