TREE PHYSIOLOGY
TRANSPIRATION
Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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Water vapor leaves the leaf through the stomata.
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Water is taken up by the roots from the soil.
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Water travels in the stem through the leaf.
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Sugar is moved throughout the plant.
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Detailed explanation-1: -1-Water is passively transported into the roots and then into the xylem. 2-The forces of cohesion and adhesion cause the water molecules to form a column in the xylem. 3-Water moves from the xylem into the mesophyll cells, evaporates from their surfaces and leaves the plant by diffusion through the stomata.
Detailed explanation-2: -There are two types of “transport” tissues in plants-xylem and phloem. Water and solutes are transported by the xylem from the roots to the leaves, and food is transported from the leaves to the rest of the plant by the phloem.
Detailed explanation-3: -Transpiration is the loss of water from the plant through evaporation at the leaf surface. It is the main driver of water movement in the xylem. Transpiration is caused by the evaporation of water at the leaf–atmosphere interface; it creates negative pressure (tension) equivalent to –2 MPa at the leaf surface.
Detailed explanation-4: -As transpiration occurs, it deepens the meniscus of water in the leaf, creating negative pressure (also called tension or suction). The tension created by transpiration “pulls” water in the plant xylem, drawing the water upward in much the same way that you draw water upward when you suck on a straw.