How is Food Transported in Plants?

Plants, like animals, need a system to transport food and nutrients to every part of their body. The process of food transportation in plants takes place mainly through a specialized tissue called phloem. Understanding how food moves inside plants is important in biology for Class 10 and Class 11 students, as it explains how plants grow, store energy, and survive.

Food Transport in Plants: Overview

• Definition: The movement of prepared food (mainly sugars like sucrose) from leaves to different parts of the plant is called translocation.
• Main Tissue Involved: Phloem, made of sieve tubes, companion cells, and phloem fibers, is responsible for transporting food in plants.
• Direction of Flow: Unlike water transport in xylem (which is unidirectional), food in phloem moves in both upward and downward directions, depending on where it is needed.

Step-by-Step Process of Food Transport in Plants

1. Photosynthesis in Leaves
   • Leaves act as the "food factories" of plants, where glucose is prepared through photosynthesis.
   • This glucose is converted into sucrose, which is easier to transport.
2. Loading into Phloem
   • The sucrose is actively loaded into the sieve tubes of phloem with the help of energy in the form of ATP.
3. Osmosis and Pressure Flow
   • The high sugar concentration in phloem draws water in by osmosis.
   • This creates a high-pressure area at the source (leaves).
4. Movement of Food
   • The pressure difference between source (leaves) and sink (roots, fruits, stems) pushes the sucrose solution towards areas of lower pressure.
   • This mechanism is called the pressure-flow hypothesis.
5. Unloading at the Sink
   • At the sink region (growing roots, fruits, seeds), sucrose is actively unloaded and used for growth, storage, or respiration.

Difference Between Transport of Food and Water in Plants