🌳 Plant Transport & Water Potential

Which of the following best describes the direction in which phloem sap can flow?

from leaves to roots or roots to leaves

Which one of the following does not correctly match the form with its function?

root hairs–support the root system

The apoplast in plant tissues may include which of the following?
cell walls and extracellular spaces

Which of the following terms describes the physical property that ultimately predicts the direction of water flow in plants?

water potential

Which of the following best predicts the movement of water across biological membranes?

water potentials

If plant cells (Ψ = -0.5 MPa) are in solution (Ψ = -0.3 MPa), what happens?

Water would move into the cells.

Which of the following is another term for solute potential?

osmotic potential

If Ψw (tissue) = -0.15 MPa and solution = -0.23 MPa, water flows:

from the tissue into the sucrose solution

Which describes the transmembrane route in plants?

Water moves out of one cell, across the cell wall and cell membrane, and enters the neighboring cell.

Why don’t plant cells burst from excess water?

Plant cells have cell walls, which provide pressure to counteract the pressure of the incoming water.

How does a flaccid cell differ from a turgid cell?

It has lower pressure potential.

If ΨP = 0.3 MPa and ΨS = -0.45 MPa, then ΨW = ?

-0.15 MPa

Important components of xylem transport?

Cohesion of water molecules and negative water potential

Ψw (tissue) = -0.15 MPa, Ψw (solution) = -0.23 MPa → water flows:

from the tissue into the sucrose solution

Most absorbed water is used to:

replacing water lost during transpiration

Main force driving water in xylem:

evaporation of water through stoma

What enters plants other than through roots?

carbon dioxide

Cell with ΨS = -0.65 MPa and constant volume in ΨW = -0.30 MPa solution:

ΨP of +0.35 MPa

What prevents gravity from overcoming transpirational pull?

Cohesion and adhesion of water molecules

Ultimate force moving water upward in trees:

Transpiration

Which is not part of the apoplastic route?

the cytoplasm of an endodermal cell

Bulk flow of water in plants is driven by:

differences in pressure between two regions

In a turgid cell:

ΨP > 0

Cohesion-tension theory says water moves due to:

the cohesive and adhesive properties of water molecules

Evaporation of water from a plant surface is:

transpiration

A plant cell in a solution with higher water potential will:

gain water and become turgid

Which statement about water potential is true?

ΨP may be either positive or negative.

When stomata close, ___________ stops.

transpiration

The ________ is the continuum of cytoplasm connected by plasmodesmata.

symplast

ΨP = 0, ΨS = -0.7 MPa → ΨW = ?

-0.7 MPa

Water droplets on terrarium glass are caused by:

Transpiration

Final barrier before water enters vascular system of roots:

an endodermal cell

Water cannot pass apoplastically through:

endodermis

Adding ______ to water always lowers the water potential.

solutes

Water moves from ____ Ψ to ______ Ψ.

lower; higher

Water in a turgid cell has ________ pressure potential.

positive