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 indicate that it is phloem sap?

Step-by-step solution

Chemical analysis of sieve tube sap proves that concentrated solution of sucrose is translocated from the place of synthesis to other parts of the plant body. Glucose and fructose are sometimes found in traces only. The amount of sucrose is more in phloem sap during the day and less in night. In xylem the amount of sucrose is in traces and also there is no diurnal fluctuation. Alkaline pH (7.8 - 8.0) is present in phloem sap whereas xylem sap is acidic.