Question

Phloem sap is mainly made of
A. Water and sucrose
B. Water and minerals
C. Oligosaccharides and hormones
D. None of the above

Answer 1

Hint: A sap is a fluid that is transported by phloem cells or xylem cells. Phloem functions to conduct prepared food materials usually from the leaves to other parts of the plant. Phloem transports only organic materials. The translocation of contents of the phloem sap is explained by the pressure-flow hypothesis.

Complete step by step answer:
Phloem transports food materials usually from leaves to other parts of the plant. It is made up of companion cells, sieve tube elements, phloem fiber, and phloem parenchyma. The phloem parenchyma stores food material and other materials like latex, resins, and mucilage.
Food, primarily sucrose, is transported by the vascular tissue phloem from a source to sink. A source is that part of the plant which synthesizes the food i.e. the leaf, and sink is the part of the plant that needs or stores the food.
Phloem sap mainly consists of water and sucrose, but other sugars, hormones, and amino acids are also transported or translocated through the phloem. When glucose is prepared at the source, it is converted into sucrose which is then moved towards the sink through active transport. This mechanism of transportation is explained by the pressure-flow hypothesis.

So, the correct answer to the above question is option (A) i.e. Water and sucrose.

Note:
Phloem cells conduct food from leaves to the other parts. The phloem sap constitutes mainly water and sucrose. When leaves prepare the food in the form of glucose, it is converted into sucrose. Sucrose along with water is then transported to other parts of the plants.