Which of the following statements best summarizes the acid growth hypothesis in an actively growing shoot?
A) Auxin stimulates proton pumps in the plasma membrane and tonoplast.
B) Auxin-activated proton pumps lower the pH of the cell wall, which breaks bonds and makes the walls more flexible.
C) Auxins and gibberellins together act as a lubricant to help stretch cellulose microfibrils.
D) Auxins activate aquaporins that increase turgor pressure in the cells.

Question

Quizplus · Accepted Answer

The acid-growth hypothesis proposes that auxin activates proton pumps in the plasma membrane and tonoplast, which lower the pH of the cell wall. This acidification results in the activation of enzymes that break bonds between cellulose microfibrils, which makes the cell wall more flexible, allowing the plant cell to elongate. Therefore, statement B best summarizes the acid growth hypothesis.

Which of the Following Statements Best Summarizes the Acid Growth