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Science · 2026 · 4 marks
CBSE 2026 · Region 4 · Set 1 · Q15
Plants exhibit movements in response to various environmental stimuli to adopt and survive in their surroundings. These movements, influenced by…
Plants exhibit movements in response to various environmental stimuli to adopt and survive in their surroundings. These movements, influenced by external factors such as light, gravity, water and chemicals are regulated by specific plant hormones. For example, the differential growth of plant parts allows them to bend, grow or orient themselves in particular directions. Roots and shoots often show contrasting response to the same stimulus, highlighting the complex mechanisms involved in plant growth and development.
(a)
Why is hydrotropism essential for plants ?
(b)
What role does auxin play in the growth of plants ?
(c)
Differentiate between movement shown by the sensitive plant and tropic movement by plants (Two points).
OR
(c)
How does movement of roots differ from that of shoots in response to gravity and light ?
Marking-scheme solution
(a) Due to hydrotropism, the roots grow towards area of water availability so that they can absorb water and minerals.
(b) Auxins promote cell elongation / Auxin regulates the tropic responses like bending (growth) of stem towards light.
(c)
| Movement by sensitive plants | Tropic Movements by plants |
| Non-directional | Directional |
| Fast | Slow |
| Growth independent movement | Growth related |
(c)
| Movement of Roots | Movement of Shoots |
| Gravity: Grows towards gravity / Positive geotropism | Gravity: Grows away from gravity / Negative geotropism |
| Light: Grows away from light / Negative phototropism | Light: Grows towards light/ Positive phototropism |
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CBSE Class 10 Science past-paper question from the 2026 board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.