PLANT PHYSIOLOGY
TRANSPORT IN PLANT
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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water enters the sieve tubes by osmosis
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sucrose enters the sieve tubes by active transport
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water leaves the sieve tubes by osmosis
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sucrose leaves the sieve tubes by active transport
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Detailed explanation-1: -The glucose prepared in the leaves is converted into sugar. The sugar in the form of sucrose is moved into the companion cells and then into the living phloem sieve tube cells by active transport. This creates a hypertonic condition in the phloem. Water in xylem vessels adjacent to phloem moves through endosmosis.
Detailed explanation-2: -According to mass flow hypothesis, sucrose moves into the living phloem sieve tube cells by active transport.
Detailed explanation-3: -1: Translocation to the sink: Sucrose is actively transported from source cells into companion cells and then into the sieve-tube elements. This reduces the water potential, which causes water to enter the phloem from the xylem.
Detailed explanation-4: -Active transport moves sucrose from a companion cell into the sieve tube elements, reducing the water potential inside. Osmosis moves water into the phloem, which increases the hydrostatic pressure. The pressure is higher nearer the source cell and lower at the sink cell end.
Detailed explanation-5: -Sucrose is loaded into sieve tube cells by active transport. Again active transport is necessary to move sucrose out of sieve tube cells.