Standard Science Primary 5 Systems

A farmer removed an outer ring of the stem of a plant, leaving the inner part intact. After two weeks, the stem above the cut swelled. Why did this happen?

A The inner wood absorbed too much water and expanded.
B The plant was storing air in the stem.
C Food made by the leaves could not be transported down past the cut.
D Water could not be transported down to the roots.
Show Worked Solution

Worked Solution

Step 1: The outer ring of a stem contains the food-carrying tubes (phloem). The inner part contains the water-carrying tubes (xylem). Step 2: Removing the outer ring removes the food-carrying tubes. Step 3: Food made by leaves (above the cut) cannot be transported downwards to the roots. Step 4: The food accumulates just above the cut, causing the swelling.

Correct answer: Food made by the leaves could not be transported down past the cut.

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