Question

The growth of the pollen tube towards the ovule is an example of

• A. Phototropism
• B. Hydrotropism
• C. Thigmotropism
• D. Chemotropism

Answer 1

The correct option is D

Chemotropism

The correct option is D.

Explanation of the correct option:

Option D:

1. Chemotropism is the movement of a plant in response to chemical stimuli and growth towards the stimulus.
2. The growth response may involve either the entire organism or only specific parts of the organism.
3. The growth response may either be positive or negative.
4. This phenomenon is observed in the growth of pollen tubes towards the ovules.
5. The ovary releases chemicals that influence the development of pollen tubes towards it.

Explanation of the incorrect options:

Option A:

1. Phototropism is the growth of an organism in response to a light stimulus and is often observed in plants.
2. In phototropism, the plant grows directionally towards the light source.
3. Usually shoots move towards the light source while roots move away from it.

Option B:

1. Hydrotropism is the plant's response to a stimulus such as a gradient in water concentration that determines the direction of plant growth.
2. Plant roots exhibit positive hydrotropism as they grow towards the water source.

Option C:

1. Thigmotropism is the directional growth of a plant that occurs in response to a mechanosensory stimulus.
2. This is found in petals, leaves, and the coiling parts of the plants.

Final answer: The growth of the pollen tube towards the ovule is an example of chemotropism.