Guard cells help in the regulation of the opening and closing of stomata for exchange of gases and loss of water from the surface of the leaves.
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The function of the guard cells are that they help to regulate the rate of transpiration by opening and closing the stomata, thus preventing excessive water loss.
Another function of guard cells is that they help to regulate the rate of transpiration by opening and closing the stomata. The guard cell opens when there is too much water. It is also adapted for gaseous exchange between plants and the environment.
For example, it opens during rainy days and closes when the weather is too dry or windy.
They also control the size of the pore.
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The job of guard cells is to open and close the stomata.
Stomata are the pores found on the leaves of plants. Their function is to allow carbon dioxide to enter the leaf (for photosunthesis) and oxygen (made by photosynthesis) to leave the leaf.
Usually stomata open during the day and close at night. This is to save water, since water vapour can escape as long as the stomata are open.
The guard cells control the size of the stomatal pore by changing their shape. When they are curved, a gap opens up between them. When they straighten (lose their curved shape) the gap is closed.
The change in shape is caused by water either entering the guard cells (to open the stomata) or leaving the guard cells (to close the stomata).
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Guard cells are specialized cells located in the leaf epidermis of plants. Pairs of guard cells surround tiny stomatal airway pores (Figure 1). These tiny holes in the surface of leaves are necessary for gas exchange into and out of the plant; carbon dioxide (CO2) enters the plant allowing the carbon fixation reactions of photosynthesis to occur. Oxygen (O2) exits the plant as a byproduct of photosynthesis. The opening and closing of the stomatal gas exchange holes is regulated by swelling and shrinking of the two surrounding guard cells (Figure 1). Due to the presence of the stomatal pores on plant leaf surfaces, water evaporates through the stomatal openings causing plants to lose water. Over 95% of water loss from plants can occur by evaporation (transpiration) through the stomatal pores. Therefore, it is important for plants to be able to balance the amount of CO2 being brought into the plant with the amount of water escaping as a result of the open stomatal pores. Hence, the guard cells are the gate keepers of the plants ability to take in CO2 from the atmosphere for photosynthesis – while regulating how much water plants lose to the atmosphere.[1][2][3][4]Opening and closure of the stomatal pore (Figure 1) is mediated by changes in the turgor pressure of the two guard cells. The turgor pressure of guard cells is controlled by movements of large quantities of ions and sugars into and out of the guard cells. When guard cells take up these solutes, the water potential (Ψ) inside the cells decreases, causing osmotic water flow into the guard cells. This leads to a turgor pressure increase causing swelling of the guard cells and the stomatal pores open (Figure 2). The ions that are taken up by guard cells are mainly potassium (K+) ions[5][6][7] and chloride (Cl-) ions.[8] In addition guard cells take up sugars that also contribute to opening of the stomatal pores.
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Guard cells are specialized cells located in the leaf epidermis of plants. Pairs of guard cells surround tiny stomatal airway pores (Figure 1). These tiny holes in the surface of leaves are necessary for gas exchange into and out of the plant; carbon dioxide (CO2) enters the plant allowing the carbon fixation reactions of photosynthesis to occur. Oxygen (O2) exits the plant as a byproduct of photosynthesis. The opening and closing of the stomatal gas exchange holes is regulated by swelling and shrinking of the two surrounding guard cells (Figure 1). Due to the presence of the stomatal pores on plant leaf surfaces, water evaporates through the stomatal openings causing plants to lose water. Over 95% of water loss from plants can occur by evaporation (transpiration) through the stomatal pores. Therefore, it is important for plants to be able to balance the amount of CO2 being brought into the plant with the amount of water escaping as a result of the open stomatal pores. Hence, the guard cells are the gate keepers of the plants ability to take in CO2 from the atmosphere for photosynthesis – while regulating how much water plants lose to the atmosphere.[1][2][3][4] Opening and closure of the stomatal pore (Figure 1) is mediated by changes in the turgor pressure of the two guard cells. The turgor pressure of guard cells is controlled by movements of large quantities of ions and sugars into and out of the guard cells. When guard cells take up these solutes, the water potential (Ψ) inside the cells decreases, causing osmotic water flow into the guard cells. This leads to a turgor pressure increase causing swelling of the guard cells and the stomatal pores open (Figure 2). The ions that are taken up by guard cells are mainly potassium (K+) ions[5][6][7] and chloride (Cl-) ions.[8] In addition guard cells take up sugars that also contribute to opening of the stomatal pores.
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The function of the guard cells are that they help to regulate the rate of transpiration by opening and closing the stomata, thus preventing excessive water loss.
Another function of guard cells is that they help to regulate the rate of transpiration by opening and closing the stomata. The guard cell opens when there is too much water. It is also adapted for gaseous exchange between plants and the environment.
For example, it opens during rainy days and closes when the weather is too dry or windy.
They also control the size of the pore.
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