Chapter 22, Problem 42A

Summary Introduction

To write:

The relation between the temperature and diameter with the tracheid function.

Introduction:

Tracheids are elongated cells in the xylem of vascular plants which help in the transport of water and mineral salts.

Explanation of Solution

On decreasing the temperature of the surroundings in which the plant is growing, the following changes are seen in the tracheids of the xylem.

The reduced temperature of about 22? to between 4? causes a rapid reduction in the radial diameter of the tracheids.

As the diameter decreases, the thickness of the cell walls of the differentiating tracheids also increases due to constant divisions in limited space.

An increase in the temperature induces an increase in both the thickness of the walls as well as the radial diameter of the tracheids. At higher temperatures, the size of the storage starch grains is smaller.

An increase in the size of the tracheid allows the tracheid to transport greater volumes of water.

Thus, an increase in radial diameter of the tracheids induces an elevation in its functions and its able to perform more efficiently.

Hence, the tracheids perform better at higher temperature with greater radii.

Conclusion

Thus, both an increase as well as a decrease in the temperature has a direct impact on the tracheids’ radius and thickness. An increase in the radii of tracheids benefits the xylem due to improved functioning of the tracheids.