NEET BIOLOGY

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PLANT PHYSIOLOGY

TRANSPORT IN PLANT

Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
The following statements refer to the movement of water from the cortex of the root into the xylem.Which of the following statements is / are true?Statement 1:Most of the water moves across the root cortex by the apoplast pathway.Statement 2:At the endodermis water has to enter the symplast pathway.Statement 3:Casparian strips in the endodermis contain the chemical lignin.
A
1, 2, and 3
B
Only 1 and 2
C
Only 2 and 3
D
Only 1
Explanation: 

Detailed explanation-1: -Water is passively transported into the roots and then into the xylem via cells of cortex. Plants absorb water from the soil by osmosis. Root hair cells are adapted for this by having a large surface area to speed up osmosis. The forces of cohesion and adhesion cause the water molecules to form a column in the xylem.

Detailed explanation-2: -Water moves into the roots from the soil by osmosis, due to the low solute potential in the roots (lower s in roots than in soil). This intake o f water in the roots increases p in the root xylem, driving water up.

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.

There is 1 question to complete.
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