Difference Between Stomata and Guard Cells

The key difference between stomata and guard cells is that the stomata are pores that locate on the epidermis of leaves, stems, etc., while the guard cells are the cells that surround and regulate the opening and closing of stomata.

Respiration and photosynthesis are two vital processes in plants. In both processes, gas exchange is important. Stomata and guard cells facilitate this job of gas exchange in plants. Here, the guard cells are parenchyma cells, and they are the cells that surround stomata. Guard cells control transpiration, which is an essential process of plants that keep plants healthy. Furthermore, the guard cells contain chlorophylls. Hence, they are capable of photosynthesizing as well.

CONTENTS

1. Overview and Key Difference
2. What are Stomata
3. What are Guard Cells
4. Similarities Between Stomata and Guard Cells
5. Side by Side Comparison – Stomata vs Guard Cells in Tabular Form
6. Summary

What are Stomata?

Stomata (singular stoma) are pores found in the epidermis of leaves, stems, and other photosynthesizing parts of the plants. Together with the guard cells, stomata control the transpiration and gas exchange in plants. During the daytime, plants produce food by photosynthesis. Photosynthesis requires water and carbon dioxide. Furthermore, photosynthesis produces oxygen as a byproduct. These CO₂ and O₂ exchange via stomata. Hence, stomata open during the daytime in response to light. As a result of hormone abscisic acid synthesizes under drought stress, stomatal openings close to prevent water loss via them.

The opening and closing of stomata mainly depend on the guard cells water potential. When guard cells absorb water and become turgid, it causes to open stomata. On the other hand, when water loses from the guard cells, guard cells become flaccid. Therefore, it causes the closing of stomata. In order to minimize transpiration, stomata mostly located in the lower epidermis of the leaves in most plants.

What are Guard Cells?

Guard cells are parenchyma cells. They are the cells that regulate transpiration in plants by opening and closing air pores called stomata. Each stoma surrounds by two guard cells.

Moreover, guard cells are specialized and important cells in plants. Guard cells not only facilitate the gas exchange, but it also facilitates the moisture exchange as well. Also, the guard cells can attain different shapes in different plant species. Some are bean-shaped while some are elongated. Here, the guard cells work according to the osmotic pressure. Therefore, water potential and potassium ion concentration are the prime factors that control the shapes of guard cells. In turn, the changing shapes of the guard cells decide the opening and closing of stomata. When the guard cells become flaccid, stomal opening closes up. But, when the guard cells become turgid, stomal opening opens up as indicated in figure 02 above.

What are the Similarities Between Stomata and Guard Cells?

• Stomata and Guard Cells are important structures found in plants.
• Both structures regulate gas exchange and transpiration.
• Also, both are found mostly on leaves.
• Furthermore, both, stomata and guard cells, work together.

What is the Difference Between Stomata and Guard Cells?

The key difference between stomata and guard cells is that the stomata are pores while the guard cells are parenchyma cells found in plants. However, they locate closely with each other and work together. The changing shapes of the guard cells decide the opening and closing of the stomata. When guard cells swell, stomata open. On the other hand, when guard cells shrink, stomata close.

The infographic shown below contains more description on the difference between stomata and guard cells.

Summary – Stomata vs Guard Cells

Stomata and guard cells are two important structures present in plants. They work together in order to fulfil their functions. In fact, the changing shape and size of guard cells regulate the opening and closing of stomatal apertures. Therefore, they both collectively facilitate the gas exchange and transpiration in plants. However, stomata are the pores that are present mostly in lower epidermis of plants leaves. Whereas, guard cells are the parenchyma cells that surround the stomata. Hence, this is the difference between stomata and guard cells.

Reference:

1.“Guard Cell.” Wikipedia, Wikimedia Foundation, 6 Oct. 2018. Available here  
2.“Guard Cells Regulate Gas and Moisture Exchange : Plants.” AskNature. Available here  

Image Courtesy:

1.”Tomato leaf stomate 1-color”By Photohound (Public Domain) via Commons Wikimedia  
2.”Guard-cell-plant”By Ali Zifan – Own work, (CC BY-SA 4.0) via Commons Wikimedia