How do vacuoles in plant cells help keep the plant upright?

Answer 1

I don't see that it is the vacuoles that keep the plant upright. I would give more credit to the cell walls and the density of the cells.

But on the assumption that I may be wrong, here is a guess. The vacuoles supply added, internal pressure to the cell's interior, firming up the cell tissue, strengthening the cell walls.

That, PLUS the fact that stem tissue is thicker and possibly more dense that other parts of the plant add to the rigidity of the plant.

Answer 2

i thought it was the cell wall that held plant cells in shape.