Guard cells use osmotic pressure to open and close stomata, allowing plants to regulate the amount of water and solutes within them. In order for plants to produce energy and maintain cellular function, their cells undergo the highly intricate process of photosynthesis . Critical in this process is the stoma.

Guard cell function Guard cells are cells surrounding each stoma. They help to regulate the rate of transpiration by opening and closing the stomata. Light is the main trigger for the opening or closing.

Essentially, guard cells are two bean-shaped cells that surround a stoma. As epidermal cells, they play an important role in gaseous exchange in and out of plant leaves by regulating the opening and closing of pores known as a stoma.

What are guard cells? A pair of guard. cells surrounds each stoma on the leaf surface. Stomata are important because they regulate the uptake of CO2 from the atmosphere for photosynthesis and also the loss of water vapour from the plant during transpiration.

Stomata are tiny holes found in the underside of leaves. Each stoma is surrounded by a pair of sausage-shaped guard cells. In bright light the guard cells take in water by osmosis and become plump and turgid . In low light the guard cells lose water and become flaccid , causing the stomata to close.

If gaurd cells stop working, then the regulation of transpiration cannot be done as the stomata cannot open or close. EXPLANATION: Guard cells are found in the stomata of leaves of the plant. They are basically turgid, swollen and have large stomatical opening.

Stomata are composed of a pair of specialized epidermal cells referred to as guard cells (Figure 3). Stomata regulate gas exchange between the plant and environment and control of water loss by changing the size of the stomatal pore.

At night, the stomata close to avoid losing water when photosynthesis is not occurring. During the day, stomata close if the leaves experience a lack of water, such as during a drought. The opening or closing of stomata occur in response to signals from the external environment.

leaves

Explanation: All surfaces of the leaf have some amount of stomata for regulating gas exchange for photosynthesis. However, the lower epidermis (the underside of the leaf) has more, because it is more often in the shade and so it is cooler, which means evaporation won’t take place as much.

The structural elements of xylem are tracheids, vessels or tracheae, xylem fibres, xylem parenchyma and rays. The tracheid is derived from a single cell and can be regarded as the basic cell type of xylem tissue.

Xylem can be defined as a complex tissue that is composed of four basic types of cell (tracheids, trachea, and xylem fibre and xylem parenchyma), remains in close association with phloem and has specialized functions like conduction of water and solutes, and mechanical strength.

Xylem is the specialised tissue of vascular plants that transports water and nutrients from the plant–soil interface to stems and leaves, and provides mechanical support and storage. The water-conducting function of xylem is one of the major distinguishing features of vascular plants.

Xylem is composed of 4 elements: tracheids, vessels, xylem parenchyma and xylem fibres.

The main function of xylem is to transport water, and some soluble nutrients including minerals and inorganic ions, upwards from the roots to the rest of the plant. Xylem cells form long tubes that transport materials, and the mixture of water and nutrients that flows through the xylem cells is called xylem sap.