Standard Science Primary 4 Systems

Siti removed the outer ring of the stem of a plant, taking away the food-carrying tubes but leaving the water-carrying tubes intact. After two weeks, she observed that the stem above the cut became swollen. Why did this happen?

A The plant was trying to grow new roots from the stem.
B Food produced by the leaves could not be transported to the roots.
C Water accumulated above the cut.
D Bacteria entered the stem and caused an infection.
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Worked Solution

Step 1: Food-carrying tubes (phloem) are located in the outer layer of the stem. Step [2-9]: Removing them prevents food from moving downwards to the roots. Step [2-9]: Food made in the leaves accumulates above the cut, causing the tissues to swell.

Correct answer: Food produced by the leaves could not be transported to the roots.

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