AP BIOLOGY

Detailed explanation-1: -Plants have vascular tissues to transport water, nutrients and minerals. Xylem transports water and mineral salts from the roots up to other parts of the plant, while phloem transports sucrose(sugar) and amino acids between the leaves and other parts of the plants.

Detailed explanation-2: -The materials like sucrose are transported by phloem sap. This flow of sap occurs in a specialised network of cells, called sieve elements. Phloem transports sucrose and amino acids up and down to the plant.

Detailed explanation-3: -The cells that make up the phloem are adapted to their function: Sieve tubes-specialised for transport and have no nuclei . Each sieve tube has a perforated end so its cytoplasm connects one cell to the next. Sucrose and amino acids are translocated within the living cytoplasm of the sieve tubes.

Detailed explanation-4: -Amino acids are transported between different organs through both xylem and phloem. This redistribution of nitrogen and carbon requires the activity of amino acid transporters in the plasma membrane. In addition, amino acids can be taken up directly by the roots.

Detailed explanation-5: -They are bordered by companion cells that carry out the cellular functions of a sieve-tube element. Phloem tubes can carry sugars and amino acids in a variety of directions; depending on where the source and the sinks are located (sometimes roots can be sources or sinks).