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

What is the primary role of the phloem in plants?

1. Transport water

2. Transport food

3. Store nutrients

4. Provide structural support

The correct answer is: Transport food

The primary role of the phloem in plants is to transport food, specifically the products of photosynthesis, such as sugars and other organic compounds, from the leaves where they are produced to other parts of the plant that need energy for growth and development. The phloem consists of living cells that form a network throughout the plant, allowing for the efficient movement of these nutrients. This function is crucial for the plant's overall health, as it ensures that every part of the plant has access to the energy required for metabolism, growth, reproduction, and repair. Unlike water, which is primarily transported by another tissue called xylem, the movement of food through the phloem supports the plant's ability to thrive in various environmental conditions. In contrast, the roles of storing nutrients and providing structural support are handled by other plant tissues. For example, storage of nutrients is the function of certain specialized tissues like parenchyma, while structural support is primarily the role of tissues like sclerenchyma and collenchyma. Therefore, the correct answer focuses on the fundamental function of phloem in nutrient transportation, highlighting its vital role in the plant's physiology.