The concept of "Active mass flow in which oxygen is required" was proposed by:

$A$ plant organ having a high concentration of food will serve as a

......... and ......... may be reversed depending on the season or the plant's need.

$A$ 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?

Assertion : Long distance flow of photoassimilates in plants occurs through sieve tubes.
Reason : Mature sieve tubes have parietal cytoplasm and perforated sieve plates.

Translocation may be affected by