Michigan Test for Teacher Certification (MTTC) Secondary Integrated Science Practice test

Which part of a plant stem is primarily involved in storage?

1. Cortex

2. Pith

3. Xylem

4. Phloem

The correct answer is: Pith

The pith is primarily involved in the storage of substances within a plant stem. It consists of parenchyma cells, which are known for their role in storing nutrients, starches, and water. This tissue is located at the center of the stem and provides a large volume that can be utilized for storage, especially in herbaceous plants. The cortex, while also capable of storage, primarily serves as a protective layer and plays a role in the transport of materials between the outer layers and the inner parts of the stem. Its main function is not as centered on storage as is the case with the pith. Xylem is dedicated to the transport of water and nutrients from the roots to other parts of the plant. It plays a crucial role in structural support and the movement of water rather than storage. Phloem is involved in the transport of sugars and other metabolic products downward from the leaves to the rest of the plant. This transport system is essential for nutrient distribution but does not serve primarily as a storage tissue. Thus, the emphasis on the pith's role in storage distinguishes it as the correct answer in this context.