Question 1

Which of the following best explains why water moves from the roots to the leaves in most vascular plants?

Accepted Answer

Water is pulled up by negative pressure generated by evaporation from leaves.

Question 2

A plant cell with a water potential of $$\psi = -0.7$$ MPa is placed in a solution with a water potential of $$\psi = -0.9$$ MPa. What will happen to the cell?

Accepted Answer

The cell will lose water and undergo plasmolysis.

Question 3

Which adaptation is most likely to be found in a desert plant such as Lithops (stone plant) to minimize water loss?

Accepted Answer

Succulent leaf tips exposed above ground, with most of the plant below ground.

Question 4

Which of the following best describes the function of the Casparian strip in plant roots?

Accepted Answer

It blocks the apoplastic route, forcing materials to pass through the endodermal cells before entering the xylem.

Question 5

Which equation correctly represents the relationship between water potential, solute potential, and pressure potential in plant cells?

Accepted Answer

$$\psi = \psi_S + \psi_P$$

Question 6

A plant is wilting because it has lost turgor pressure. What is the most likely cause?

Accepted Answer

The plant has lost water faster than it can replace it through the roots.

Question 7

Which of the following is a direct result of the cohesion-tension mechanism in plants?

Accepted Answer

Water is pulled upward through the xylem from roots to leaves.

Question 8

Why do florists recommend cutting flower stems under water before placing them in a vase?

Accepted Answer

To prevent air bubbles from breaking the cohesion of water molecules in the xylem.

Question 9

Which of the following best describes the role of proton pumps in plant cells?

Accepted Answer

They create a hydrogen ion gradient that can be used to transport nutrients against their concentration gradients.

Question 10

In the pressure flow hypothesis of phloem transport, what causes water to enter the sieve tube elements at the source?

Accepted Answer

Osmosis due to high sucrose concentration in the sieve tube elements.

Question 11

Which of the following scenarios would result in the highest water potential ($$\psi) in a U-$$tube experiment?

Accepted Answer

The side with pure water and no applied pressure.

Question 12

Which of the following is most directly responsible for the movement of water from the soil into the root hairs?

Accepted Answer

Osmosis due to a water potential gradient.

Question 13

During the summer, which of the following best describes the direction of phloem sap flow in a sugar maple tree?

Accepted Answer

From leaves to roots, flowers, or fruit.

Question 14

Which of the following is a function of the phloem in plants?

Accepted Answer

Transport of sugars and signaling molecules from sources to sinks.

Question 15

A plant cell has $$\psi_S = -0.7$$ MPa and $$\psi_P = 0.5$$ MPa. What is the water potential ($$\psi) of $$the cell?

Accepted Answer

$$\psi = -0.2$$ MPa

Question 16

Which of the following best explains why vertical leaf orientation is advantageous in sunny environments?

Accepted Answer

It reduces sun damage and allows light to reach lower leaves.

Question 17

Which of the following is NOT a route by which water and minerals can travel through plant tissues?

Accepted Answer

Vacuolar route

Question 18

What is the main reason that plants close their stomata during drought conditions?

Accepted Answer

To prevent excessive water loss through transpiration.

Question 19

Which of the following best describes the role of mycorrhizae in plant roots?

Accepted Answer

They aid in the absorption of water and minerals, helping plants colonize land.

Resource Acquisition and Transport in Vascular Plants

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