Biology STAAR (State of Texas Assessments of Academic Readiness) Practice Test

What does phloem primarily transport in plants?

1. Water

2. Minerals

3. Food

4. Oxygen

The correct answer is: Food

Phloem primarily transports food in plants, specifically the products of photosynthesis, such as glucose. This transport occurs throughout the plant, moving from the leaves—where photosynthesis occurs—to other parts such as the stems and roots, where the food is either used for energy or stored for later use. The phloem's role is crucial for the plant's growth and development, as it ensures that all parts of the plant receive the necessary nutrients to function properly. The food transported by the phloem can take various forms, including sugars and other organic compounds that support the plant's metabolism and growth processes. In contrast, other options like water, minerals, and oxygen serve different functions within the plant. Water and minerals are primarily transported by xylem tissue, which is responsible for moving these substances from the roots to the aerial parts of the plant. Oxygen is a byproduct of photosynthesis and is used in cellular respiration, but it is not a substance that phloem transports. Thus, the specific function of phloem in transporting food distinguishes it from these other processes.