Topic 9.2: Transport in the Phloem of Plants
Essential Idea: Structure and function are correlated in the phloem in plants.
At SHS, Topic 9.2 is taught in the following class unit(s):
Statements & Objectives:
9.2.U1 Plants transport organic compounds from sources to sinks.
9.2.U2 Incompressibility of water allows transport along hydrostatic pressure gradients.
9.2.U3 Active transport is used to load organic compounds into phloem sieve tubes at the source.
9.2.U4 High concentrations of solutes in the phloem at the source lead to water uptake by osmosis.
9.2.U5 Raised by hydrostatic pressure causes the contents of the phloem to flow toward sinks.
9.2.A1 Structure-function relationships of phloem sieve tubes.
9.2.S1 Identification of xylem and phloem in microscope images of stem and root.
9.2.S2 Analysis of date from experiments measuring phloem transport rates using aphid stylets and radioactively-labelled carbon dioxide.
9.2.NOS Developments in scientific research follow improvements in apparatus-experimental methods for measuring phloem transport rates using aphid stylets and radioactively-labelled carbon dioxide were only possible when radioisotopes became available.