NEETBiologyAnatomy of Flowering PlantsMCQ+4 / −1
Function of companion cells is :
- AProviding water to phloem
- BLoading of sucrose into sieve elements
- CLoading of sucrose into sieve elements by passive transport
- DProviding energy to sieve elements for active transport
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Correct answer: B
Companion cells move sugar and amino acids into and out of the sieve elements. In “source” tissue such as leaf companion cells use transmembrane proteins to take up sugar and amino acids by active transport. Movement of sugars in the phloem begins at the source, where sugars are loaded (actively transported) into a seive tube. Loading sets up a water potential gradient that facilitates movement of sugar.
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