Question 1

Which of the following best explains why land plants evolved specialized transport tissues?

Accepted Answer

Land plants needed to move water and minerals between roots and shoots due to their exposure to different environments.

Question 2

Which process is responsible for the passive movement of water across a plant cell membrane?

Accepted Answer

Osmosis

Question 3

What is the primary function of the proton pump in the plasma membrane of plant cells?

Accepted Answer

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

Question 4

Which equation correctly represents water potential ($$\Psi) in $$plant cells?

Accepted Answer

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

Question 5

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

Accepted Answer

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

Question 6

Which route allows substances to move from cell to cell through plasmodesmata in plant tissues?

Accepted Answer

Symplastic route

Question 7

What is the main function of the endodermis in plant roots?

Accepted Answer

To act as a selective checkpoint for minerals entering the vascular tissue.

Question 8

Which statement best describes the direction of xylem and phloem sap flow in plants?

Accepted Answer

Xylem sap flows unidirectionally from roots to leaves, while phloem sap can flow in multiple directions depending on source and sink locations.

Question 9

Transpiration in plants is most directly responsible for which of the following?

Accepted Answer

Driving the upward movement of water and minerals through the xylem.

Question 10

Which of the following best describes the role of root pressure in plants?

Accepted Answer

It generates a positive pressure that can push xylem sap upward, especially at night when transpiration is low.

Question 11

A plant species has a transpiration-to-photosynthesis ratio of 600:1. What does this mean?

Accepted Answer

The plant loses 600 grams of water for every gram of $$\mathrm{CO_2$}$$ assimilated into organic molecules.

Question 12

Which of the following is a direct result of potassium ion ($$\mathrm{K^+}) $$movement into guard cells?

Accepted Answer

Water enters guard cells by osmosis, causing stomata to open.

Question 13

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

Accepted Answer

Active transport using a proton gradient and cotransport proteins.

Question 14

In a plant, which organ typically acts as a sugar source?

Accepted Answer

A mature leaf undergoing photosynthesis.

Question 15

Which of the following best describes the movement of phloem sap?

Accepted Answer

It moves from sugar sources to sugar sinks, and the direction depends on the location of these organs.

Question 16

A multi-step scenario: A plant root cell uses ATP to pump $$\mathrm{H^+}$$ ions out of the cell, creating a membrane potential. Which subsequent event is most likely to occur?

Accepted Answer

Cations such as $$\mathrm{K^+}$$ are driven into the cell by the membrane potential.

Question 17

Which of the following is NOT a function of the vacuole in mature plant cells?

Accepted Answer

Regulating the traffic of materials in and out of the cell.

Question 18

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

Accepted Answer

Increasing the temperature and wind speed around the plant.

Question 19

A plant is observed to have guttation droplets on its leaves early in the morning. What is the most likely explanation?

Accepted Answer

Root pressure has pushed xylem sap out of the leaves because transpiration is low.

Transport in Plants: Mechanisms and Pathways

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