Question

The growth of pollen tubes towards ovules is due to

• A. hydrotropism
• B. chemotropism
• C. geotropism
• D. phototropism

Answer 1

The correct option is B

chemotropism

The correct option is B.

Explanation for the correct option:

1. Chemotropism refers to the development of plant components in response to a chemical input.
2. Chemotropism is demonstrated by the development of a pollen tube in the direction of the ovule in response to a sweet stimulus.
3. The pollen tube is growing in the direction of the stimulus, demonstrating positive chemotropism.

Explanation for the incorrect options:

Option A:

1. The ability of roots to draw water and nutrients from the soil is essential for terrestrial plants to survive.
2. Hydrotropism, or the directed development of roots in response to a moisture gradient, starts in the root cap with the detection of the gradient.

Option C:

1. Geotropism is the movement or growth of plant parts in response to the force of gravity
2. While shoots exhibit negative geotropism when they grow upward, roots exhibit positive geotropism when they grow downward.

Option D:

A plant can maximize photosynthetic light absorption in the aerial section and water and nutrient uptake in the roots by using phototropism, or the differential cell elongation displayed by a plant organ in response to directed blue light.

Final answer: The growth of pollen tubes towards ovules is due to chemotropism.