Advanced Science Primary 5 Systems

A farmer removed the outer ring of the stem of a fruit tree. A few weeks later, the stem above the cut swelled up. What caused the swelling?

A The plant was storing excess mineral salts.
B Air could not enter the stem.
C Food made by the leaves accumulated above the cut.
D Water from the roots accumulated above the cut.
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Worked Solution

Step 1: Removing the outer ring of a stem removes the food-carrying tubes (phloem). Step 2: The leaves continue to make food during photosynthesis. Step 3: This food is transported downwards but is blocked by the cut. Step 4: The accumulated food causes the stem just above the cut to swell.

Correct answer: Food made by the leaves accumulated above the cut.

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