Insulin. Insulin is a hormone made by the beta cells in the pancreas. It is the key that opens the doors of cells and allows glucose to get into the cell. Each cell needs glucose to function. Carbohydrates in food are broken down into glucose which enters the blood stream.
The pericycle is a cylinder of parenchyma or sclerenchyma cells that lies just inside the endodermis and is the outer most part of the stele of plants.
The water-conducting cells of the primary xylem are dif-ferentiated as a solid core in the center of young dicotroots. In a cross-section of a dicot root, the central core ofprimary xylem often is somewhat star-shaped, with one ortwo to several radiating arms that point toward the pericy-cle (figure 38.19).