Transpiration stream
Transpiration is the The process in which a liquid changes state and turns into a gas. of water at the surfaces of the spongy mesophyll cells in leaves, followed by loss of water vapour through the Tiny holes in the epidermis (skin) of a leaf. They control gas exchange by opening and closing and are involved in loss of water from leaves. Singular is stoma..
Water moves through the Narrow, hollow, dead tubes with lignin, responsible for the transport of water and minerals in plants. in a continuous The flow of water in the xylem from the roots to the leaves..
root → stem → leaf
Transpiration produces a tension or ‘pull’ on the water in the xylem vessels by the leaves. Water molecules are Able to stick together. so water is pulled up through the plant.
The transpiration stream has several functions. These include:
- transporting mineral Electrically charged particle, formed when an atom or molecule gains or loses electrons.
- providing water to keep cells Enlarged and swollen with water. Having turgor. Description of a plant cell in which the vacuole has swollen due to water gain by osmosis. by filling vacuoles in order to support the plant and stop it wilting
- providing water to leaf cells for A chemical process used by plants to make glucose and oxygen from carbon dioxide and water, using light energy. Oxygen is produced as a by-product of photosynthesis. Algae subsumed within plants and some bacteria are also photosynthetic.
- keeping the leaves cool by evaporation
Rate of transpiration
If the rate of The loss of water from leaves by evaporation through the stomata. increases, the rate of absorption of water by the root increases too. Factors that affect the rate of transpiration also affect water uptake by the plant. If water is scarce, or the roots are damaged, a plant may wilt.
Root hair cells
The A specialised cell that increases the surface area of the root epidermis to improve the uptake of water and minerals. are where most water absorption happens. They are long and thin so they can penetrate between soil particles, and they have a large surface area for absorption of water through osmosis.
Water passes from the soil water to the root hair cell’s The living substance inside a cell (not including the nucleus). by The movement of water molecules across a partially-permeable membrane from a region of low solute concentration to a region of high solute concentration.. This happens because the soil water has a higher concentration than the root hair cell cytoplasm.