How do the guard cells regulate the opening and closing of stomatal pores?

By BYJU'S Exam Prep

Updated on: September 25th, 2023

The guard cells surround a pore called a stomatal aperture by which the gas exchange happens. By incoming water in the guard cells, they swell and become banana-like curved surfaces because of which the stomatal pore opens. Plant respiration is regulated by stomata and guard cells.

Guard cells

  1. In the epidermis of leaves are specialised cells called guard cells.
  2. They help with the gas exchange.
  3. They encircle an orifice called a stomatal aperture, via which gases are exchanged.
  4. When water enters the guard cells, they expand until they resemble a curved banana surface, which causes the stomatal aperture to open.
  5. The stomatal opening is closed when the guard cells become floppy and straight from water loss.

Functions of stomata

  1. The stomatal opening is the mechanism through which CO2 and O2 are exchanged.
  2. Through the pull of transpiration, it controls water loss.
  3. The amount of available moisture in the atmosphere affects when the stomatal aperture opens and closes.
  4. It permits the transport of CO2 and releases O2 into the atmosphere during photosynthesis.
  5. Water loss through pores is stopped at night by stomata closure.



How do the guard cells regulate the opening and closing of stomatal pores?

A pore known as a stomatal aperture, through which gas exchange takes place, is surrounded by guard cells. The guard cells enlarge and assume a banana-like curved surface when water enters them, which causes the stomatal pore to open.

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