A plant stem is given light from one side and it bends towards the light. What is the correct reason for this bending?
Answer and explanation
Correct answer: More auxin on the shaded side causes greater growth
The governing concept is positive phototropism controlled by auxin. With one-sided light, auxin becomes concentrated on the shaded side of a young shoot. In shoots, this promotes greater cell elongation on that side. The shaded side therefore grows faster than the illuminated side, producing unequal growth and bending the stem toward the light. Option B is correct; plant stems do not have blood flow, and neither cell death nor root pressure explains this directional curvature.
Frequently asked questions
What is the correct answer to this question?
More auxin on the shaded side causes greater growth
Why is this the correct answer?
The governing concept is positive phototropism controlled by auxin. With one-sided light, auxin becomes concentrated on the shaded side of a young shoot. In shoots, this promotes greater cell elongation on that side. The shaded side therefore grows faster than the illuminated side, producing unequal growth and bending the stem toward the light. Option B is correct; plant stems do not have blood flow, and neither cell death nor root pressure explains this directional curvature.
Which subject and chapter does this question cover?
This is a Class 10 Science question. Chapter: Control and Coordination. Topic: Plant hormones.
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