13.3 Plant Organs and functions - ROOTS

13.3 Plant Organs and Their Functions ROOTS! Functions: absorb water and minerals from the soil physically support and anchor plants store carbohydrates produce compounds like hormones Outer root layers Endodermis Only one cell thick Surrounded by waterproof band called casparian strip Creates barrier for water and minerals – control point Cortex just inside the epidermis Composed of ground tissue (parenchyma) Transport & water storage, minerals, and food Cross Sections of Roots vascular cylinder - contains xylem and phloem to transport water and minerals up or sugars down is in the center of both monocot and dicot roots surrounded by the endodermis- regulates lateral movement of water pericycle- meristematic tissue which produces secondary roots and secondary xylem and phloem cambium- only in dicot roots- produces secondary xylem and phloem cortex- parenchyma cells which store nutrients; will die and disappear in older dicot roots epidermis- outer layer- can be replaced after secondary growth with “bark”; can have extensions growing out called root hairs which absorb water and nutrients Types: Taproot a root that increases in diameter and length as it grows down e.g. Carrot Fibrous root a root that branches to the sides, a main root is not obvious e.g. grass Modified root Food and water storage e.g. potatoes Structure: Primary root- first root developed from the seed Secondary root- smaller root branches growing sideways from primary root Growth of a Root: root cap- protects root as it pushes through soil apical meristem- divides to produce new cells zone of elongation- cells produced in meristem get larger zone of maturation- full grown cells differentiate into vascular, ground, or dermal tissue; root hairs develop to increase surface area of water absorption Time lapse radish seeds sprouting, top and roots growing http://www.youtube.com/watch?v=d26AhcKeEbE http://www.youtube.com/watch?v=eDA8rmUP5ZM http://www.youtube.com/watch?v=z5GIcpLsVp4 http://www.youtube.com/watch?v=fPTJ3qD1ikk&NR=1 Time-lapse Pea/Root Growth http://www.youtube.com/watch?v=RmF-wetl_RA&NR=1 Garlic Clove Root Growth with Time Lapse. Homework Read p 552-554 Ans. p 554 #13-16