34. Vascular Plant Transport

The purpose of the xylem is to __________.

The proton pump in plant cells __________.

A plant cell placed in a solution with a higher water potential will __________.

The water potential of a cell is defined by the equation Ψ = Ψ_S + Ψ_P. Which of the following statements is true?

A cell has a pressure potential of 0 and a solute potential of -0.7 MPa. What is its water potential?

In a turgid cell, __________.

Why does rapid movement of water molecules across the plasma membrane of a plant cell occur?

In order to be transported throughout a plant, viruses exploit __________.

The cytoplasmic continuum connecting neighboring cells is called the __________.

The continuum of cell walls connecting neighboring cells is defined as the __________.

Which of the cells below are involved with bulk flow?

When referring to phloem transport, what creates the sink in roots?

Cells that are specialized for the transport of sugar between apoplast and symplast are __________ cells.

In an apple tree that is producing sugars, sugar might flow from __________ to __________.

Which of the following describes how some plants are adapted to arid environments?

Stomata open during the day in response to __________.

What process contributes directly to the turgor pressure that opens and closes stomata?

The rate of transpiration is expected to be greatest on a __________ day.

What is the ultimate source of energy that moves water upward in the trunk of a tree?

During winter, tree sap can sometimes freeze, and cavitation (the formation of an air pocket) may occur. Which of the following mechanisms of sap transport would you expect to be most immediately affected by cavitation?

The last thing all water and solute molecules pass through before they enter the vascular system of roots and move upward to the leaves is __________.

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

In a plant root, the one structure that water cannot move past via the apoplast is the __________.

Normally, when an aphid feeds by puncturing plant tissues, it does not have to suck the sap out. If an aphid, however, inserted its feeding tube in the wrong place, the fluid in the aphid's guts could be sucked out through the feeding tube. What could explain this phenomenon?

One of your friends has a terrarium on her windowsill containing various houseplants. She wonders why the glass is often fogged with water droplets. What would you tell her is the cause of the droplets?

Root pressure is attributable to __________.

Which of the following conditions will result in the fastest transport through the xylem in a tree, assuming adequate water supply in the roots?

What keeps the force of gravity from overcoming transpirational pull?

Fill in the blanks in this concept map to help you tie together key concepts concerning transport in plants.

Explain how guard cells limit water loss from a plant on a hot, dry day. How can this be harmful to the plant?

Transpiration is fastest when humidity is low and temperature is high, but in some plants it seems to increase in response to light as well. During one 12-hour period when cloud cover and light intensity varied frequently, a scientist studying a certain crop plant recorded the data in the table (top right). (The transpiration rates are grams of water per square meter of leaf area per hour.) Do these data support the hypothesis that the plants transpire more when the light is more intense? If so, is the effect independent of temperature and humidity? Explain your answer. (Hint: Look for overall trends in each column, and then compare pairs of data within each column and between columns.)

Agriculture is by far the biggest user of water in arid western states, including Colorado, Arizona, and California. The populations of these states are growing, and there is an ongoing conflict between cities and farm regions over water. To ensure water supplies for urban growth, cities are purchasing water rights from farmers. This is often the least expensive way for a city to obtain more water, and some farmers can make more money selling water than growing crops. Discuss the possible consequences of this trend. Is this the best way to allocate water for all concerned? Why or why not?