Asked in ETEA MDCAT 2006 2006

The opening and closing of stomata are controlled by which of the following factor(s)?

Correct answer: A. Sugar

  • A. Sugar
  • B. pH
  • C. Potassium
  • D. All of the above

Explanation

The opening and closing of stomata are primarily controlled by the conversion of starch to sugar and vice versa in guard cells. During the daytime, sugar increases osmotic pressure, leading to stomata opening, while at night, starch reduces osmotic pressure, causing stomata closure. While pH and potassium are important factors in plant physiology, they are not the main drivers of stomata regulation through the starch-sugar interconversion mechanism.

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About Plant Nutrition and Transport

Plants require macronutrients and micronutrients for growth, and mineral deficiencies produce recognizable symptoms. Transport involves water and minerals through xylem by transpiration pull, cohesion and adhesion, while phloem translocates sugars from sources to sinks. Root pressure and transpiration are distinct mechanisms.

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