Ch32 Plant Nutrition & Transport

Which of the following allows plants to be selective about the molecules that enter the xylem?

A waxy barrier in the plant root.

_____ is responsible for the movement of sugars from leaves to taproots; _____ is responsible for the movements of sugar from taproots to leaves.

Bulk flow ... bulk flow

In roots the _____ forces water and solutes to pass through the plasma membranes of _____ cells before entering the _____.

Casparian strip ... endodermis ... xylem

_____ cells are the cells that regulate the opening and closing of stomata, thus playing a role in regulating transpiration.

Guard

_____ bonds are responsible for the cohesion of water molecules.

Hydrogen

_____ transport(s) sugars from leaves to, for example, taproots.

Phloem

Which of the following describes the correct order in which water moves through a plant and into the atmosphere?

Root, xylem, leaf cells, air space inside leaves, outside air.

_____ provide(s) the major force for the movement of water and solutes from roots to leaves.

Transpiration

At a sugar sink, sugar is removed from phloem by _____.

active transport

The water pressure that pushes water and sugar from sugar source to sugar sink is referred to as _____.

bulk flow - the force responsible for the translocation that occurs in phloem.

Which of the following terms describes water molecules sticking to other water molecules?

cohesion

Transpiration

describes the process by which water is lost from plants by evaporation.

Cohesion

describes the tendency of water molecules to stick to each other.

Adhesion

describes the tendency of water molecules to stick to the fibers of plant cell walls.

The continuum of spaces between cell walls of neighboring cells is the __________ route of water and solute transport from root hairs to xylem.

extracellular

As turgor pressure increases in guard cells, the transpiration rate would be expected to __________.

increase

The function of a root hair is to

increase the surface area available for absorption in plant roots.

The loss of water from plants through transpiration

is an important part of the mechanism that pulls water from a plant's roots to its leaves.

Which of these are symbiotic associations?

mycorrhizae

Water moves into phloem by _____.

osmosis

Which of these processes is responsible for leaves being considered sugar sources?

photosynthesis

The channels indicated by the pointer, are _____.

plasmodesmata - Water and ions can pass from cell to cell via these channels. Also, recall that plasmodesmata are a type of cell junction.

When considering the source-to-sink model of phloem transport, what plant structures can act as either a source or a sink depending on the season?

roots - Roots, such as the beet root in the figure below, may be modified for food storage. When storing food, they act as a sink. As the stored food is utilized by the plant, roots act as a source.

Sugar moves from leaves into the _____ of _____ by _____.

sieve-tube members ... phloem ... active transport

In a sugar sink, such as a taproot, sugar is converted into _____.

starch

Guard cells actively open and close the stomata of leaves. What delicate internal balance do these guard cells control with their actions?

the balance between water uptake and gas exchange

Stomata open during the day in response to __________.

the uptake of K+ by guard cells

An undergraduate student had a terrarium on her windowsill containing various houseplants. She wondered why the glass was often fogged with water droplets. A friend who had taken a biology class, tried to explain that it was because of _____.

transpiration

A botanist discovered a mutant plant that is unable to produce the material that forms the Casparian strip. This plant is __________.

unable to control the amounts of water and solutes it absorbs

the movement of water and ions through the root _____.

via the apoplastic (extracellular) route