Plants exhibit movements in response to various environmental stimuli to adopt and survive in their…
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).
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.
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(c)
Movement by sensitive plants Tropic Movements by plants
Non-directional Directional
Fast Slow
Growth independent movement Growth related
(Any two points, any other difference)
OR
(c)
Movement of Roots Movement of Shoots
Gravity: Grows towards gravity / Gravity: Grows away from gravity /
Positive geotropism Negative geotropism
Light: Grows away from light / Light: Grows towards light/ Positive
Negative phototropism phototropism