What substances are transported by phloem?

Phloem transports organic nutrients, particularly sucrose, from photosynthetic cells to non-photosynthetic parts of the plant.

Phloem is a complex tissue in plants that primarily functions in the transport of organic nutrients from the photosynthetic leaf cells, where they are produced, to the other parts of the plant that are not photosynthetic. This process is known as translocation. The main substance transported by phloem is sucrose, a type of sugar that serves as a primary energy source for plant cells.

In addition to sucrose, phloem also transports amino acids and other organic molecules, including hormones and signalling molecules that regulate plant growth and development. These substances are loaded into the phloem tissue in the leaves and then transported to various parts of the plant, including the roots, stems, and developing fruits and seeds.

The transport of substances in the phloem is an active process, meaning it requires energy. This energy is provided by ATP, a molecule that stores and releases energy in cells. The substances are loaded into the phloem cells against a concentration gradient, which is why energy is needed. Once in the phloem, the substances are carried along by the flow of water, driven by differences in pressure.

In summary, phloem plays a crucial role in the life of a plant by transporting organic nutrients, particularly sucrose, as well as other organic molecules and hormones, from the photosynthetic cells to the non-photosynthetic parts of the plant. This process ensures that all parts of the plant receive the nutrients they need to grow and function properly.