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Structure, Functions, Types & Mechanism of Stomata MCQ - Practice Questions with Answers
Edited By admin | Updated on Sep 18, 2023 18:34 AM | #NEET
Quick Facts
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12 Questions around this concept.
Solve by difficulty
Which of the following has an active role in stomatal opening?
Basis of stomatal opening is
In the mechanism of opening of stomata, the important factor is
Which part of the leaf is meant for photosynthesis and gaseous exchange?
Which of the following facilitates opening of stomatal aperture?
Perception of blue light in plants causes
Opening and closing of stomata occur due to turgor changes in _____.
Grass leaves curl inwards during very dry weather. Select the most appropriate reason for the following:
In the given figure, which component has thin outer walls and highly thickened inner walls?
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This ebook serves as a valuable study guide for NEET exams, specifically designed to assist students in light of recent changes and the removal of certain topics from the NEET exam.
Download EBookGiven below is a diagram of the stomatal apparatus.Match the labels with the corresponding names of the components.
Choose the correct combination.
(A) 1-Stomatal pore: 2- Guard cell; 3- Epidermal cell; 4- subsidiary cell
(B) 1-Guard cell: 2- Stomatal pore; 3- Subsidiary cell; 4- Epidermal cell
(C) 1-Subsidiary cell: 2- Guard cell; 3- Stomatal pore; 4- Epidermal cell
(D) 1-Guard cell: 2- Stomatal pore; 3- Epidermal cell; 4- subsidiary cell
Concepts Covered - 0
Mechanism of Stomatal Opening
- Stomatal opening and closing is a physiological function dependent on the light.
- They open in light and close in the dark. Such stomata are called photoactive.
- In succulents plants, the stomata are scotoactive. They open at night and close during the day time.
- Stomata open and close as a result of osmosis.
- Under hot and dry conditions, when water loss due to evaporation is high, stomata must close to prevent dehydration.
- Guard cells actively pump potassium ions (K +) out of the guard cells and into surrounding cells.
- This causes water in the enlarged guard cells to move osmotically from an area of low solute concentration (guard cells) to an area of high solute concentration (surrounding cells).
- The loss of water in the guard cells causes them to shrink. This shrinkage closes the stomatal pore.
- When conditions change such that stomata need to open, potassium ions are actively pumped back into the guard cells from the surrounding cells.
- Water moves osmotically into guard cells causing them to swell and curve.
- The outer wall of guard cells bend outwards because it is thin and elastic.
- The inner wall does not bend as it is thick and inelastic.
- This bending of outer wall causes opening of stomatal pore.
- The opening of the stoma is also aided due to the orientation of the microfibrils in the cell walls of the guard cells.
- Cellulose microfibrils are oriented radially rather than longitudinally making it easier for the stoma to open.
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