HORTICULTURE SCIENCE
PLANT BIOLOGY
Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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water upward
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sugar upward
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water downward
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sugar downward
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Detailed explanation-1: -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. Cohesion (water sticking to each other) causes more water molecules to fill the gap in the xylem as the top-most water is pulled toward the stomata.
Detailed explanation-2: -Once water is in the xylem, it travels upwards-against the force of gravity-towards the rest of the plant. Water is able to move against gravity due to two forces: tension and cohesion. Tension is a ‘sucking force’ which is created when water evaporates from leaves (transpiration), pulling more water into the leaf.
Detailed explanation-3: -Continuous transpiration occurring in all of the leaves of a plant creates a negative pressure in the water column (xylem). This exerts an upward pull on the water column, called transpiration pull. And thus, the water present in the xylem column transports up to the tip of the stem, leaves, etc.
Detailed explanation-4: -Tracheids and vessels are the main water-conducting components of the xylem. They are dead cells as they do contain any protoplasm. They are elongated tube-like structures having a lignified wall.