Xylem and Phloem
Lesson Objectives
Content Objective: The structure of the xylem and phloem aid in the movement of molecules around the plant and how adhesion, cohesion, active transport, osmosis and hydrostatic pressure aid in this.
Language Objective: Explain structure of the xylem and phloem aid in the movement of molecules around the plant and how adhesion, cohesion, active transport, osmosis and hydrostatic pressure aid in this.
Syllabus Details:
First
Transpiration is the inevitable consequence of gas exchange in the leaf
Plants transport water from the roots to the leaves to replace losses from transpiration
The cohesive property of water and the structure of the xylem vessels allow transport under tension
The adhesive property of water and evaporation generate tension forces in leaf cell walls
Active uptake of mineral ions in the roots causes absorption of water by osmosis
Second
Plants transport organic compounds from sources to sinks
Incompressibility of water allows transport along hydrostatic pressure gradients
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
Raised by hydrostatic pressure causes the contents of the phloem to flow toward sinks
Structure-function relationships of phloem sieve tubes
Last
Models of water transport in xylem using simple apparatus including blotting or filter paper, porous pots and capillary tubing
Drawing the structure of primary xylem vessels in sections of stems based on microscope images
Measurement of transpiration rates using potometers ( Practical 7)
Design of an experiment to test hypothesis about the effects of temperatures or humidity on transpiration
Analysis of data from experiments measuring phloem transport rates using aphid stylets and radioactively-labelled carbon dioxide
Identification of xylem and phloem in microscope images of stem and root
Activites
Activity 1 - Notes on Transpiration
Xylem
Activity 2 - Water transport in the xylem - Model Making
Need things such as filter paper, straws, capillary tubing, plastic bags, balloons
Activity 3 - Transpiration Lab
Activity 4 - Translocation Pre - Notes (Second set of syllabus details)
Please take notes on the following syllabus details:
Plants transport organic compounds from sources to sinks
Incompressibility of water allows transport along hydrostatic pressure gradients
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
Raised by hydrostatic pressure causes the contents of the phloem to flow toward sinks
Structure-function relationships of phloem sieve tubes
Resources:
Xylem
Phloem
Fuse School - Translocation - The best place to start.
Translocation in the Phloem - Second best place to start
Activity 5 - Adding a Voice Over
Please add a voice over to this video:
Animation - Transport of water and sugar in plants.mp4
Home Learning
A. Strengthen Your Skills
B. Expand Your Knowledge
Xylem and Phloem Growth and Development - from living to dead cells