Nitrogen-fixing bacteria actually reside in localized swellings, or root nodules , of legume plants. Differentiate between the endodermis and the exodermis of the root cortex. Due to the presence of the Casparian strip in the walls of endodermal cells, water can move into the vascular cylinder only by crossing the plasma membrane and diffusing through the cytoplasm. Transpiration is the evaporation of water from stems, leaves, and other plant parts. The cohesion-tension theory explains how water moves upward in an unbroken column through xylem to the tops of tall trees.
Transpiration occurs mostly at stomata , tiny epidermal passageways of leaves and stems.
Explain the mechanism by which stomata open during daylight and close during the night. Under stressful conditions, abscisic acid can cause guard cells to give up potassium ions and close stomata. Carbohydrates are stored as starch in most plants. Sucrose is the main form in which sugars are transported through most plants. Describe the role of sieve tube members and companion cells in translocation.