In flowering plants the growth of the pollen tube toward ovules is an example of :a)hydrotropismb)chemotropismc)phototropismd)geotropismCorrect answer is option 'B'. Can you explain this answer?

Question

Answer

Chemotropism can be reffered as a movement of a plant part towards the chemical stimulus which generally occurs when pollen tube grows towards the ovules. Hence option (b)  is correct.

Answer

Option(b)becoz

chemotropism The growth or movement of a plant or plant part in response to a chemical stimulus. An example is the growth of a pollen tube down the style during fertilization in response to the presence of sugars in the style.

Answer

The movement of plant or plant parts in response to chemical stimuli is called chemotropism.
When pollen grain comes in contact with the stigma, the ovary produces a positive chemical response for the pollen grain, which in turn gives out the pollen tube that grows towards the ovary and carries the male gamete to the egg cell for
fertilization.

Thus, the correct answer is option D.

Answer

Pollen Tube Growth in Flowering Plants: An Example of Chemotropism

Chemotropism is the growth or movement of an organism or its parts in response to a specific chemical stimulus. In the case of flowering plants, the growth of the pollen tube towards the ovules is an example of chemotropism.

Explanation:

Pollen Transfer and Pollination:
- In flowering plants, the transfer of pollen from the anther to the stigma is a crucial step in the process of sexual reproduction.
- Pollen grains, which contain the male gametes, are produced in the anther of the flower.
- These pollen grains need to reach the stigma of the same or a compatible flower for successful pollination.

Formation of the Pollen Tube:
- Once a pollen grain lands on the stigma, it germinates and forms a pollen tube.
- The pollen tube grows down through the style, a long tube-like structure that connects the stigma to the ovary.
- The growth of the pollen tube is directed towards the ovule, which contains the female gametes.

Chemotropism in Pollen Tube Growth:
- The growth of the pollen tube is guided by chemical signals emitted by the ovules.
- The ovules release a chemical attractant called a 'chemoattractant' that acts as a guidance cue for the pollen tube.
- The pollen tube senses and responds to this chemoattractant by growing towards the source of the chemical signal.
- This directional growth of the pollen tube towards the ovules is an example of chemotropism.

Significance of Chemotropism in Pollen Tube Growth:
- Chemotropism ensures the successful fertilization of the ovule by directing the growth of the pollen tube towards the female reproductive structures.
- It helps in achieving efficient pollination and prevents wasteful growth in other directions.
- The precise guidance provided by chemotropism increases the chances of successful fertilization, leading to the formation of seeds and fruits in flowering plants.

Conclusion:
The growth of the pollen tube towards the ovules in flowering plants is an example of chemotropism. This phenomenon ensures the successful fertilization of the ovules by directing the growth of the pollen tube towards the female reproductive structures. Chemotropism plays a crucial role in the process of pollination and is essential for the reproduction and propagation of flowering plants.

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