Role of Phloem in Transportation of Food in Plants

The phloem is a type of vascular tissue in plants responsible for the transportation of food, primarily in the form of sucrose, from source to sink. Here’s a simplified explanation based on the NCERT syllabus:

1. Source: The source is usually the leaves, where photosynthesis occurs and glucose is produced. This glucose is converted into sucrose for transport.
2. Loading of Sucrose: Sucrose is actively transported into the phloem sieve tubes from the source cells.
3. Translocation: The movement of sucrose through the phloem is termed translocation. This process is energy-dependent and occurs through a mechanism called pressure-flow hypothesis or mass flow hypothesis. The loading of sucrose causes water to enter the phloem from the xylem, creating a high-pressure area.
4. Sink: The sink is the part of the plant where the sucrose is needed, such as roots, fruits, and seeds. The sucrose is unloaded at the sink, where it can be used for growth, storage, or energy.

Thus, the phloem plays a crucial role in the transportation of food from leaves to other parts of the plant where it is needed.