PLANTS
TRANSPORT IN PLANTS
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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To give structural support to the phloem vessels
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To connect the phloem vessels to the xylem vessels
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Their function is unknown
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To act as “life support systems” for phloem cells which have lost most of their normal cell functions
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Detailed explanation-1: -Since the sieve tube element loses its nucleus and ribosomes, the companion cell is the cell responsible for the metabolic life of the sieve elements, including the transport of carbohydrates in and out the sieve elements [7].
Detailed explanation-2: -Companion cells are found along with sieve tube elements in the phloem. The main function of companion cells is to maintain pressure gradient in the sieve tube elements.
Detailed explanation-3: -4.3 The companion cells-sieve elements complex It must function in several roles, including phloem loading and unloading, long-distance transport, and as a quality control center for monitoring the nature of substances passing into and out of the phloem.
Detailed explanation-4: -Companion cells move sugar and amino acids into and out of the sieve elements. In ‘source’ tissue like leaf companion cells use transmembrane proteins to require up sugar and amino acids by transport. Loading is a setup of a water potential gradient that facilitates movement of the sugar.
Detailed explanation-5: -Once the sucrose enters the companion cells, it can diffuse along the cytoplasmic links between these cells and their adjacent sieve tube members via the plasmodesmata. Therefore, companion cells are adapted for their role as they contain many mitochondria that provide energy via cellular respiration.