Question

From the given situations, identify 'Chemotropic' and 'Geotropic' movements in parts of plants, respectively:
(i) Growth of pollen tube towards ovule.
(ii) Movement of sunflower towards sunlight.
(iii) Movement of root towards Earth/Gravity.
(iv) Movement of leaves due to breeze.

• A. (i) and (iii) respectively
• B. (iii) and (i) respectively
• C. (i), (ii) and (iii), (iv) respectively
• D. (i), (iii) and (ii), (iv) respectively

Hint:

Tropic movements in plants:

• Chemotropism \(\Rightarrow\) Chemical stimulus (e.g., pollen tube growth)
• Geotropism \(\Rightarrow\) Gravity (roots +, shoots -)
• Phototropism \(\Rightarrow\) Light (shoots +, roots -)
• Thigmotropism \(\Rightarrow\) Touch (tendrils)

Answer 1

The Correct Option is A

Step 1: Understand the types of plant movements.

• Chemotropism: Growth or movement of a plant part in response to a chemical stimulus.
• Geotropism (Gravitropism): Growth or movement of a plant part in response to gravity.
• Phototropism: Growth or movement in response to light.
• Thigmotropism: Growth or movement in response to touch or contact.

Step 2: Analyze each given situation.

• (i) Growth of pollen tube towards ovule: This is Chemotropism because the pollen tube grows in response to chemical signals (sugars, calcium) released by the ovule.
• (ii) Movement of sunflower towards sunlight: This is Phototropism (response to light), not chemotropism or geotropism.
• (iii) Movement of root towards Earth/Gravity: This is Geotropism (positive geotropism as roots grow downward in response to gravity).
• (iv) Movement of leaves due to breeze: This is a physical movement (hygroscopic or mechanical), not a tropic movement. It is not a growth movement.

Step 3: Identify chemotropic and geotropic movements.

• Chemotropic movement: (i) Growth of pollen tube towards ovule
• Geotropic movement: (iii) Movement of root towards Earth/Gravity

Step 4: Match with options.
Option (A) says (i) and (iii) respectively, which correctly identifies chemotropic and geotropic movements in that order. Final Answer: (A) (i) and (iii) respectively