MICROANATOMY

Detailed explanation-1: -Phloem is comprised of cells called sieve-tube elements. Phloem sap travels through perforations called sieve tube plates. Neighboring companion cells carry out metabolic functions for the sieve-tube elements and provide them with energy.

Detailed explanation-2: -Food and other organic substances (e.g., some plant hormones and even messenger RNAs) manufactured in the cells of the plant are transported in the phloem. Sugars (usually sucrose), amino acids and other organic molecules enter the sieve elements through plasmodesmata connecting them to adjacent companion cells.

Detailed explanation-3: -Phloem transports carbohydrates, produced by photosynthesis and hydrolysis of reserve compounds, to sink tissues for growth, respiration and storage. At photosynthetic tissues, carbohydrates are loaded into phloem (Rennie and Turgeon 2009), a process that raises the solute concentration.

Detailed explanation-4: -Phloem is a highly specialised vascular tissue that forms an interconnected network of continuous strands throughout a plant’s body. It transports sugars, nutrients, and a range of signalling molecules between leaves, roots, flowers, and fruits. As a result, phloem is central to plant function.