The mechanisms that regulate the loading of sucrose from the apoplast to the sieve- tube members by sucrose- H⁺symporters are not well understood. Of the following possible regulatory factors, which is least likely to be of direct importance?

Question

Quizplus · Accepted Answer

The density of direct cytoplasmic connections between companion cells and sieve-tube members, while important for other aspects of phloem function, is least likely to directly regulate the loading of sucrose by sucrose-H^+/symporters. These symporters function at the plasma membrane to transport sucrose into the sieve-tube members, a process more directly influenced by sucrose concentration, turgor pressure, and the availability of symporter proteins.

The Mechanisms That Regulate the Loading of Sucrose from the Apoplast