Chapter 22, Problem 41A

Summary Introduction

To write:

The effects of temperature on the diameter of developing tracheid cells.

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.

Conclusion

Thus, both an increase as well as a decrease in the temperature has a direct impact on the tracheids’ radius and thickness.