Question 1

Which of the following statements best explains why annual growth rings are visible in the cross-section of a tree trunk?

Accepted Answer

They result from seasonal changes in the activity of the vascular cambium, producing xylem with different cell sizes.

Question 2

Which tissue is responsible for the increase in diameter (secondary growth) of woody plants?

Accepted Answer

Vascular cambium

Question 3

A plant cell with a water potential of $$\Psi = -0.7$$ MPa is placed in a solution with $$\Psi = 0$$ MPa. What will happen to the cell?

Accepted Answer

Water will move into the cell, making it turgid.

Question 4

Which of the following best describes the function of lignin in plant cell walls?

Accepted Answer

It provides structural support and waterproofing.

Question 5

What is the main mechanism responsible for the upward movement of water in xylem from roots to leaves?

Accepted Answer

Transpiration-cohesion-tension mechanism

Question 6

Which of the following is NOT a function of the cork cambium?

Accepted Answer

Generating secondary xylem

Question 7

In the pressure-flow hypothesis for phloem transport, what drives the movement of sugar solution from source to sink?

Accepted Answer

A gradient of water potential created by active loading and unloading of sugars

Question 8

Which of the following best describes the difference between heartwood and sapwood?

Accepted Answer

Heartwood is darker, non-conducting, and filled with resins, while sapwood is lighter and conducts xylem sap.

Question 9

Which pathway allows water to move through the cell walls and intercellular spaces without crossing any membranes until the endodermis?

Accepted Answer

Apoplast pathway

Question 10

A woody eudicot stem is observed to have three annual rings. Which tissue is responsible for producing these rings, and what do they represent?

Accepted Answer

Vascular cambium; secondary xylem produced each growing season

Question 11

Which of the following is a correct statement about water potential ($$\Psi) in $$plants?

Accepted Answer

Water moves from regions of higher to lower water potential.

Question 12

Which of the following is a living cell at maturity and is involved in phloem transport?

Accepted Answer

Sieve-tube element

Question 13

Which of the following best describes the role of rays produced by the vascular cambium?

Accepted Answer

They facilitate lateral (radial) transport of nutrients and water.

Question 14

Which of the following is true regarding the movement of water and minerals in the xylem?

Accepted Answer

It is a passive process driven by differences in water potential.

Question 15

Which of the following is a correct sequence for the pathway of water from soil to atmosphere in a herbaceous plant?

Accepted Answer

Soil → root hair → cortex → endodermis → xylem → atmosphere

Question 16

Which hormone is responsible for causing stomatal closure during dry conditions by triggering the loss of K$$^+$$ from guard cells?

Accepted Answer

Abscisic acid

Question 17

Which of the following is a real-world application of lignin?

Accepted Answer

It is removed from wood pulp to make paper.

Question 18

Which of the following best explains why water and ions must cross a cell membrane at the endodermis before entering the xylem?

Accepted Answer

The Casparian strip is impermeable to water and ions, forcing them through the plasma membrane for selective uptake.

Question 19

Which of the following is NOT a characteristic of secondary xylem?

Accepted Answer

It is alive at maturity.

Question 20

Which of the following best describes the role of mycorrhizal fungi in plant roots?

Accepted Answer

They increase the surface area for absorption of minerals and water.

Secondary Growth and Transport in Plants: Structure and Function

Study Guide - Practice Questions