Essential Idea:
Structure and function are
correlated in the phloem of plants
Understandings:
- Plants transport organic compounds from sources to sinks
- Active transport is used to load organic compounds into phloem sieve tubes at the source
- High concentrations of solutes in the phloem at the source lead to water uptake by osmosis
- Incompressibility of water allows transport along hydrostatic pressure gradients
- Raised hydrostatic pressure causes the contents of the phloem to flow towards sinks
Applications:
- Structure-function relationships of phloem sieve tubes
Skills:
- Identification of xylem and phloem in microscope images of stem and root
- Analysis of data from experiments measuring phloem transport rates using aphid stylets and radioactively-labelled carbon dioxide