Question

A few drops of sap were collected by cutting across a plant stem by a suitable method. The sap was tested chemically. Which one of the following test results indicates that it is phloem sap?
A. Low refractive index
B. Absence of Sugar
C. Acidic
D. Alkaline

Answer 1

Sap is a form of fluid that transports in xylem cells, vessel elements or tracheids or phloem sieve tube elements of a plant. These cells transport water and nutrients throughout the plant. Sap is fluid which is very different from latex, resin, or cell sap. It is a separate substance which is separately produced, and it is produced with different components and different functions.

Complete step-by-step answer:
After cutting the plant stem region a few drops of sap is collected and got tested chemically. The process or method of cutting is known as bleeding. Bleading is the process in which sap and its solution get exudation. It means when a watery solution or a sap region is taken from the plant region and this process in simple terms is known as bleeding. And exudation is removal from a cut or injured part of the plant. So, according to this question, when a cut is made from a plant stem region and sap is taken from it and here rot pressure and phloem pressure plays an important role into it. Local pressure maintains the respiration rate in all plant parts and xylem region as well as latex region or resin region. These entire regions in plants got damaged after cutting. Because due to sap all these regions get disturbed and cycles of these also get disturbed. Due to the disturbances and cutting down of all those regions occur which further results in our pumping nature. Pumping in this occurs in protons. Due to the pumping of protons the companion cells start moving toward the outer environment. When the companion cells move towards the outer environment the sap in that region become alkaline in nature.

So, the correct option is option D. Alkaline.

Note: Phloem is the living tissue in vascular plants that transports the soluble organic compounds made during photosynthesis and known as photosynthates, in particular the sugar sucrose, to parts of the plant where needed. This transport process is called translocation. It was introduced by carl nagelli in 1858.