9.2: Transport in the phloem of plants

key vocab

prior learning & Retrieval practice

S1: Identification of xylem and phloem in microscope images of stem and root.

Exercise 1: Complete the exercises below

A1: Structure–function relationships of phloem sieve tubes.

Essential idea: Structure and function are correlated in the phloem of plants.

Exercise 2: Review the Quizlet deck below

U1: Plants transport organic compounds from sources to sinks.

U2: Incompressibility of water allows transport along hydrostatic pressure gradients.

U3: Active transport is used to load organic compounds into phloem sieve tubes at the source.

U4: High concentrations of solutes in the phloem at the source lead to water uptake by osmosis.

U5: Raised hydrostatic pressure causes the contents of the phloem to flow towards sinks.

Exercise 3: Outline transport in the phloem of plants from source to sink.

S2: Analysis of data from experiments measuring phloem transport rates using aphid stylets and radioactively-labelled carbon dioxide.

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. (1.8)