Plant Transport 1: Moving Water from Soil to the Vascular Cylinder (BIOL1104)

Plant Transport 1 : Moving Water from Soil to the Vascular Cylinder See Phelan, What is Life? Dr. Paul Ulrich Georgia State University  Outline 1. How do plan...

Plant Transport 1 : Moving Water from Soil to the Vascular Cylinder See Phelan, What is Life? Dr. Paul Ulrich Georgia State University  Outline 1. How do plants move water and minerals from soil to the xylem? 2. How do plants move water and minerals up stems? 3. How is sugar moved in the plant body?  Root structure Eudicot root ROOT HAIRS Cross section of a root Root hairs Dermal tissue increase surface Audesirk, Pearson Education area of the root Ground tissue in contact with Vascular tissue soil in order to Phloem increase Xylem transport of water and nutrients. Vascular cylinder – bundle of xylem & phloem (surrounded by endodermis) in the center of roots and stems See Phelan, What is Life?  path of water into the cylinder Water moves freely in spaces between most cells, but the vascular cylinder is sealed off by waxy barriers between endodermal cells water must pass through endodermal cells to get to xylem endodermis Xylem soil Audesirk, Pearson Education Key concept: “water follows the minerals”  Plants move minerals from soil to xylem K+, Ca2+, NO3-, and PO43- to cross a cell membrane, charged substances must move via channels and pumps Depending on the soil, dissolved minerals in the soil water may be less concentrated than in the root cells. WHEN MINERAL CONCENTRATIONS ARE WHEN MINERAL CONCENTRATIONS ARE GREATER OUTSIDE THE CELL GREATER INSIDE THE CELL Outside root cell ATP ATP Inside root cell Minerals move into plant cells by facilitated In this situation, root cells must use ATP to pump diffusion. minerals in by active transport. Phelan, What is Life?  In some cases, plants use ATP to move Q1 minerals from soil water into root cells. Why does it require ATP? a) Mineral atoms are very heavy. b) Mineral concentrations in root cells are higher than in soil water. c) Roots need energy to release minerals from small pieces of rock. d) Minerals have negative charges that must be neutralized with ATP. Getting into the “elevator” : osmosis from soil to vascular cylinder Because cytoplasm of root cells has a lower water concentration than soil water in soil, water moves into root cells. How does water then get into the vascular cylinder? 1. Endodermal cells pump minerals into xylem 2. Mineral concentrations in xylem exceed that of root cells (water concentration in xylem decreases) 3. Water moves in by osmosis Xylem in vascular cylinder root water minerals  In groups of 2 or 3, draw bars on the graphs that show concentrations of water (left graph) and solutes (right graph) in soil water, root cells, and xylem. SOLUTE concentration WATER concentration Soil Root Xylem Soil Root Xylem Water Cells Water Cells When you have completed your graphs, show them to another group and explain the patterns you drew.  Which one should have the Q2 highest water concentration? a) Soil water b) Root cell c) Xylem d) They are all are equal  Which should have the highest solute Q3 concentration? a) Soil water b) Root cell c) Xylem d) They are all are equal