Questions & Answers

Glycolate induces opening of stomata in
(a) Presence of oxygen
(b) Low carbon dioxide concentration
(c) High carbon dioxide concentration
(d) Absence of carbon dioxide

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Hint: During the process of photosynthesis light energy is captured and used to convert carbon dioxide, water, and minerals into oxygen and energy-rich compounds.

Complete answer:
Glycolate induces the opening of stomata in low carbon dioxide concentration. Glycolic acid is formed in the guard cell which helps in the opening of stomata. Glycolate is produced in the low concentration of carbon dioxide and it provides the energy required for the opening of the guard cells.
The Krebs cycle takes place in the mitochondria. The formation of glycolate gives rise to carbohydrates. Pyruvate undergoes a series of cyclic reactions liberating carbon dioxide. Through the electron transport system, a complete breakdown of glucose results in the production of ATP or Adenosine Triphosphate. This ATP helps in the active pumping of water in the guard cells and the stomatal pore opens. When the reverse of this process takes place, the stomatal pore closes.

So, the correct answer is ‘low carbon dioxide concentrations’.

Note: -The stomata allow the exchange of gases by acting as an entryway for carbon dioxide and exit for oxygen produced. It also regulates water movement through transpiration.
-The theory of opening and closing of guard cells was suggested by Zelitch in 1963.
-In a plant, there are no respiratory systems so different plant parts breathe separately. As the direction of diffusion depends upon environmental conditions and the requirement of the plant, during daytime the carbon dioxide released through respiration is used for photosynthesis while the oxygen released during photosynthesis is used for respiration.
-So the exchange of gases is not a dominating factor. At night no photosynthesis occurs so carbon dioxide released during respiration moves to the environment.