Water movement in plants

Which water potential gradient correctly describes the path of water through a plant?

 

Ψsoil > Ψroot > Ψstem > Ψleaf > Ψatmosphere

Which event triggers stomatal OPENING?

Blue light activating H⁺-ATPase proton pumps in guard cells

According to the cohesion-tension theory, what generates the force that pulls water up the xylem?

Tension created by transpiration from the leaves

Water potential (Ψ) is expressed relative to pure water at atmospheric pressure, which has a Ψ of…

0 MPa

Matric potential (Ψm) results from…

water adsorbing to surfaces such as cell walls, starch and proteins via hydrogen bonding

Adding solutes to water causes solute potential (Ψs) to…

become more negative

A plasmolysed cell has a pressure potential of about…

0

During stomatal closing, which of the following occurs?

K⁺ moves out of guard cells, water exits by osmosis, and guard cells become less turgid

Which combination would MOST increase the rate of transpiration?

Bright light, high temperature, low humidity, wind

An osmotically active substance (OAS) is a solute that…

cannot pass a selectively permeable membrane when water can

Water moves from areas of ______ water potential to areas of ______ water potential.

higher; lower

Active transport differs from passive transport because active transport…

moves solutes against a concentration or electrical gradient using energy

Water molecules sticking to other water molecules is called ______, while water sticking to xylem walls is called ______.

cohesion; adhesion

What percentage of the water entering a plant is typically transpired?

More than 90%

Imbibition, the first step in seed germination, is driven by…

adhesion of water to hydrophilic colloids such as cellulose, starch and proteins

Positive pressure potential inside a plant cell is called ______, which helps the cell maintain its shape.

turgor pressure

Osmosis is the diffusion of water through a semipermeable membrane from a region where water is…

more concentrated to a region where it is less concentrated

Which statement describes passive transport?

It moves solutes down their concentration or electrical gradient without metabolic energy

Why does gravity potential (Ψg) become more important in taller plants?

Gravity pulls water downward, adding about 0.01 MPa/m of resistance to overcome

In the pressure-flow hypothesis, sugars move in the phloem from…

source to sink by bulk flow driven by a turgor pressure gradient

Guttation fluid can be distinguished from dew because guttation fluid…

is xylem sap containing dissolved substances