Question 1

Which of the following best explains why the evolution of roots and shoots in land plants created a new challenge for internal transport?

Accepted Answer

Roots and shoots exposed different parts of the plant to different resources, requiring specialized transport between them.

Question 2

Which of the following is NOT a level at which transport occurs in plants?

Accepted Answer

Transport between different plant species.

Question 3

Which process is responsible for the net uptake or loss of water by a plant cell?

Accepted Answer

Osmosis

Question 4

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

Accepted Answer

Water will enter the cell by osmosis, causing it to become turgid.

Question 5

Which of the following best describes the function of the proton pump in the plasma membrane of plant cells?

Accepted Answer

It uses ATP to pump $$\mathrm{H^+}$$ ions out of the cell, creating a proton gradient and membrane potential.

Question 6

Which route allows water and minerals to move through the cytoplasm of plant cells, connected by plasmodesmata?

Accepted Answer

Symplastic route

Question 7

The endodermis in plant roots serves as a selective barrier. What is its main function?

Accepted Answer

It regulates the selective passage of minerals from the cortex into the vascular tissue.

Question 8

Which of the following statements about xylem transport is correct?

Accepted Answer

Xylem sap moves unidirectionally from roots to leaves, primarily driven by transpiration.

Question 9

A maple tree loses more than 200 liters of water per hour during the summer. What is the main process responsible for this water loss?

Accepted Answer

Transpiration

Question 10

Root pressure can cause guttation in some plants. Which of the following best describes guttation?

Accepted Answer

The exudation of liquid water from the tips or edges of leaves due to positive root pressure.

Question 11

The transpiration-to-photosynthesis ratio is a measure of:

Accepted Answer

How much water is lost per gram of $$\mathrm{CO_2$}$$ assimilated by photosynthesis.

Question 12

Which of the following best explains why guard cells open and close stomata?

Accepted Answer

Changes in turgor pressure due to potassium ion movement cause guard cells to change shape.

Question 13

Which of the following statements about phloem transport is correct?

Accepted Answer

Phloem sap can move in either direction, from sugar sources to sugar sinks.

Question 14

In most plants, what is the most prevalent solute in phloem sap?

Accepted Answer

Sucrose

Question 15

Which mechanism is primarily responsible for loading sucrose into sieve-tube members in the phloem?

Accepted Answer

Active transport using a proton gradient and cotransport proteins

Question 16

A plant is exposed to a toxin that inhibits ATP production. Which of the following processes would be most directly affected?

Accepted Answer

Active transport of ions across cell membranes

Question 17

If a plant's endodermis is damaged and becomes non-selective, what is the most likely consequence?

Accepted Answer

Harmful substances from the soil could enter the vascular tissue unchecked.

Question 18

Which of the following best describes the direction of phloem transport in a plant?

Accepted Answer

From a sugar source to a sugar sink, which can vary depending on the plant's needs.

Question 19

A scientist measures the concentration of sucrose in the phloem and in the sink tissues of a plant. She finds that the concentration is higher in the phloem. What does this indicate about the movement of sucrose?

Accepted Answer

Sucrose will diffuse from the phloem into the sink tissues.

Question 20

Which of the following equations best represents the water potential ($$\Psi) in $$plant cells?

Accepted Answer

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

Transport in Plants: Mechanisms and Pathways

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