Question 1

Which of the following best describes the equation for water potential ($$\Psi) in $$plant cells?

Accepted Answer

$$\Psi = \Psi_s + \Psi_p$$

Question 2

A plant cell is placed in a solution with a lower solute concentration than its cytoplasm. What will happen to the cell's turgor pressure and why?

Accepted Answer

Turgor pressure will increase because water will enter the cell due to higher water potential outside.

Question 3

Which component of water potential is directly affected by the presence of dissolved solutes?

Accepted Answer

Solute potential ($$\Psi_s)$$

Question 4

Why does the xylem in most plants typically operate under negative pressure (tension)?

Accepted Answer

Transpiration from leaves creates a pulling force that draws water upward.

Question 5

Which of the following best explains why trees can transport water to great heights?

Accepted Answer

The cohesion-tension mechanism, where water molecules stick together and are pulled up by transpiration.

Question 6

If the solute potential ($$\Psi_s) of a $$cell is $$-0.7$$ MPa and the pressure potential ($$\Psi_p) is$$ $$0.5$$ MPa, what is the total water potential ($$\Psi$$)?

Accepted Answer

$$\Psi = -0.2$$ MPa

Question 7

Which adaptation is most likely found in xerophytes to reduce water loss?

Accepted Answer

Thick cuticle and sunken stomata

Question 8

What is the primary function of guard cells in plant leaves?

Accepted Answer

Regulating the opening and closing of stomata to control gas exchange and water loss

Question 9

Which of the following scenarios would most likely result in wilting of a plant?

Accepted Answer

Transpiration exceeds water uptake, causing loss of turgor pressure in cells

Question 10

A scientist measures the water potential in the soil as $$-0.1$$ MPa and in the root xylem as $$-0.5$$ MPa. In which direction will water move, and why?

Accepted Answer

Water will move from the soil into the root xylem because water moves from higher to lower water potential.

Question 11

Which process is directly responsible for the majority of water loss from plants?

Accepted Answer

Transpiration through stomata

Question 12

How does abscisic acid (ABA) help plants respond to drought conditions?

Accepted Answer

ABA signals guard cells to close stomata, reducing water loss

Question 13

Which of the following would most likely increase the rate of transpiration in a plant?

Accepted Answer

High temperature, low humidity, and wind

Question 14

Why is the phloem important for plant survival?

Accepted Answer

It transports sugars and other organic molecules from sources to sinks.

Question 15

Which of the following best describes the effect of closing stomata during the day?

Accepted Answer

Reduces water loss but also limits CO$$_2$$ uptake and photosynthesis

Question 16

A plant is exposed to dry, windy conditions. Which physiological response is most likely to occur?

Accepted Answer

Stomata close to reduce water loss

Question 17

Which of the following is a direct consequence of the cohesion-tension theory in plants?

Accepted Answer

Water is pulled upward through the xylem due to transpiration and cohesion between water molecules.

Question 18

If a plant's leaf cells have a water potential of $$-1.2$$ MPa and the surrounding air has a much lower water potential, what will happen?

Accepted Answer

Water will evaporate from the leaf cells into the air, increasing transpiration.

Question 19

Which of the following best explains why succulent plants can survive in arid environments?

Accepted Answer

They store water in specialized tissues and often have CAM metabolism to reduce water loss.

Transpiration and Water Transport in Vascular Plants (Chapter 36 Study Notes)

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