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NCERT Class 10 Science Control and Coordination: In-text questions (page 108) Solutions
AI-written, checked on 23 Oct 2026
Solutions written by Shishya, checked — not the board's official answers
Step-by-step working for every question of In-text questions (page 108) in NCERT's Class 10 Science book, chapter “Control and Coordination”, written by Shishya. Each question is in our own short words; open the NCERT chapter for the exact wording and figures.
How these were checked: the solutions were drafted with AI and then read and corrected on 23 Oct 2026. Every numerical final answer is recomputed from the question's own numbers by a calculator check that runs before each release; proofs and explanations were read, not machine-checked. The NCERT textbook is the authority — if something here disagrees with it, follow the book.
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In-text (page 108) Q1
What are plant hormones?
- Plant hormones are chemical substances produced by plants in very small quantities.
- These chemicals are synthesized in one part of the plant and transported to another part.
- They regulate various physiological processes such as growth, development, and reproduction.
- Examples of plant hormones include auxins, gibberellins, cytokinins, and abscisic acid.
Answer: Plant hormones are chemical messengers produced in small amounts that regulate growth and development.
In-text (page 108) Q2
How is the movement of the leaves of a sensitive plant different from the movement of a shoot towards light?
- The sensitive plant (Mimosa pudica) moves its leaves in response to touch or physical contact.
- This movement is called thigmonasty and is a rapid, reversible response that does not involve growth.
- The shoot moves towards light in a process called phototropism.
- This movement is slow and involves differential growth on the two sides of the shoot.
- The leaf movement is a nastic movement triggered by a stimulus at a specific point, while shoot movement is a tropic movement directed by the source of light.
- Thus, the sensitive plant's movement is a fast, non-growth-based response, whereas the shoot's movement is a slow, growth-based response.
Answer: The sensitive plant's leaf movement is a rapid, reversible nastic response to touch without growth, while the shoot's movement towards light is a slow, growth-based tropic response.
In-text (page 108) Q3
Give an example of a plant hormone that promotes growth.
- Plant hormones are chemical substances that regulate growth and development in plants.
- Auxin is a major plant hormone that is produced in the shoot tips.
- Auxin promotes cell elongation which leads to the overall growth of the plant.
- Therefore, auxin is the example of a plant hormone that promotes growth.
Answer: Auxin
In-text (page 108) Q4
How do auxins help a tendril grow around a support?
- A tendril is a thin, coiling part of a plant that helps it climb by wrapping around a support.
- When the tendril touches a support, the side that is in contact with the support receives a signal.
- This signal causes auxin, a plant hormone, to accumulate on the side of the tendril that is away from the support.
- Auxin promotes cell elongation in the region where it is present.
- As a result, the cells on the side away from the support grow faster and become longer than the cells on the side touching the support.
- This uneven growth causes the tendril to bend towards the support.
- The tendril continues to grow and coil around the support, helping the plant to climb.
Answer: Auxin accumulates on the side of the tendril away from the support, causing those cells to elongate faster than the cells on the side touching the support, which makes the tendril bend and coil around the support.
In-text (page 108) Q5
Design an experiment to show hydrotropism.
- Take a transparent tray and fill it with a layer of moist cotton or soil.
- Place a few germinating seeds (like bean or mustard) on the cotton with their roots facing downward.
- Place a small piece of wet cotton or a water dropper on one side of the tray to create a moisture gradient.
- Keep the tray in a dark place to avoid phototropism interfering with the experiment.
- Observe the growth of the roots over 2 to 3 days.
- You will notice that the roots bend and grow towards the side with the wet cotton or water source.
- This directional growth of roots in response to water is called hydrotropism.
Answer: The roots grow towards the source of water, demonstrating positive hydrotropism.
Other exercises in this chapter
- In-text questions (page 105) — 5 questions
- In-text questions (page 111) — 4 questions
- End-of-chapter exercises — 12 questions
← Control and Coordination: notes, practice and all exercises
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