1.Punctuality a.The last person to come into the class later than me will teach the class for 2 minutes on a selected topic by yours truly. b.Homework to be returned during the first Theory lesson of the week. 2.Cleanliness 3.Courtesy a.If you need to speak, raise your hands. b.If someone is speaking, open your ears, and not your mouth. 4.Consistency a.You must always have your notes with you. 5.Commitment a.If you are tasked to do something, I expect it to be done with all your effort.

Learning Objectives By the end of the lesson, you should be able to: i)*Describe the pressure flow hypothesis in translocation (transport of sucrose in the phloem tissue). ii)Describe three lines of evidence that phloem tissue is involved in translocation: using aphids, radioisotopes and ringing experiment

6.1.1Vascular Bundle Structure & Function 6.1.2Stem Internal Structure 6.1.3Root Internal Structure 6.1.4Leaf Internal Structure in Relation to Vascular Bundle Arrangements 6.1.1Vascular Bundle Structure & Function 6.1.2Stem Internal Structure 6.1.3Root Internal Structure 6.1.4Leaf Internal Structure in Relation to Vascular Bundle Arrangements 6.2.1Water Potential 6.2.2Overview of Water Movement 6.2.3Water Movement in Roots 6.2.4Mechanism of Water & Mineral Transport in Stems i) Root Pressure ii) Capillary Action iii) Transpiration & Transpiration Pull 6.2.5Water Movement in Leaves 6.2.6Factors Influencing Water Movement and Water Loss 6.2.7Wilting 6.2.1Water Potential 6.2.2Overview of Water Movement 6.2.3Water Movement in Roots 6.2.4Mechanism of Water & Mineral Transport in Stems i) Root Pressure ii) Capillary Action iii) Transpiration & Transpiration Pull 6.2.5Water Movement in Leaves 6.2.6Factors Influencing Water Movement and Water Loss 6.2.7Wilting 6.4.1Hydrophytic Leaves 6.4.2Xerophytic Leaves 6.4.1Hydrophytic Leaves 6.4.2Xerophytic Leaves 6.3.1Pressure Flow Hypothesis 6.3.2Evidence for Sucrose Translocation 6.3.1Pressure Flow Hypothesis 6.3.2Evidence for Sucrose Translocation

Xylem is UNIDIRECTIONAL. Phloem is BIDIRECTIONAL. Do you think transpiration pull is a model that can sufficiently explain phloem transport? What do you think is necessary in order for phloem sap to move? XYLEM PHLOEM COMPANION CELL

Yes! You need a Driving Force! In order for a Driving Force to be established… You need to have some form of GRADIENT.

Difference in Hydrostatic Pressure 1) SUGAR SOURCE: Parts of plant where excess sugar being released or produced. 2) SUGAR SINKS: Parts of plant where sugar is consumed or stored. Sugar moves to SOURCE to SINK.

Phloem Loading 1.Sugar is first “loaded” from SUGAR SOURCE into Phloem by the Companion Cell. 2.Requires Energy. 3.Phloem  Water Potential becomes MORE NEGATIVE 4.Water from Xylem enters Phloem by Osmosis. 5.High Hydrostatic Pressure in Phloem XYLEM PHLOEM COMPANION CELL HIGH HYDROSTATIC PRESSURE

Phloem Unloading 1.Sugar is unloaded from Phloem into storage tissues 2.Requires Energy 3.Phloem  Water Potential becomes LESS NEGATIVE 4.Water from Phloem returns to Xylem by Osmosis. 5.Low Hydrostatic Pressure in Phloem XYLEM PHLOEM COMPANION CELL LOW HYDROSTATIC PRESSURE

Difference in Hydrostatic Pressure 1.Phloem Loading in Sugar Sources: High Hydrostatic Pressure 2.Phloem Unloading in Sugar Sinks: Low Hydrostatic Pressure BULK FLOW or MASS FLOW hill.com/sites/ /student_view0/ chapter38/animation_- _phloem_loading.html

Aphids extract phloem sap by inserting their proboscis into the phloem. 1.Anaesthetize aphids with CO 2 while they are feeding. 2.Sever aphid body with laser. 3.Phloem sap flows out of severed proboscis by hydrostatic pressure. 4.Analyse phloem sap.. Voila! Sugars found! 1. Use of Aphids

2. Use of Radioactive Carbon Isotopes 1. Carbon-14, radioactive isotope of carbon. 2. Incorporated into CO Administered to plant. 4. Section plant and put on photographic plate.

Recall: Where is the position of the Phloem relative to the Xylem in a Dicot Stem? 3. Bark-Ringing Experiments Epidermis Pith Vascular Bundle Cortex

Learning Objectives Are you able to? i)*Describe the pressure flow hypothesis in translocation (transport of sucrose in the phloem tissue). ii)Describe three lines of evidence that phloem tissue is involved in translocation: using aphids, radioisotopes and ringing experiment

Learning Objectives By the end of the lesson, you should be able to: i)*Describe adaptations of leaf structure to the availability of water (hydrophytic and xerophytic leaves)

6.1.1Vascular Bundle Structure & Function 6.1.2Stem Internal Structure 6.1.3Root Internal Structure 6.1.4Leaf Internal Structure in Relation to Vascular Bundle Arrangements 6.1.1Vascular Bundle Structure & Function 6.1.2Stem Internal Structure 6.1.3Root Internal Structure 6.1.4Leaf Internal Structure in Relation to Vascular Bundle Arrangements 6.2.1Water Potential 6.2.2Overview of Water Movement 6.2.3Water Movement in Roots 6.2.4Mechanism of Water & Mineral Transport in Stems i) Root Pressure ii) Capillary Action iii) Transpiration & Transpiration Pull 6.2.5Water Movement in Leaves 6.2.6Factors Influencing Water Movement and Water Loss 6.2.7Wilting 6.2.1Water Potential 6.2.2Overview of Water Movement 6.2.3Water Movement in Roots 6.2.4Mechanism of Water & Mineral Transport in Stems i) Root Pressure ii) Capillary Action iii) Transpiration & Transpiration Pull 6.2.5Water Movement in Leaves 6.2.6Factors Influencing Water Movement and Water Loss 6.2.7Wilting 6.4.1Hydrophytic Leaves 6.4.2Xerophytic Leaves 6.4.1Hydrophytic Leaves 6.4.2Xerophytic Leaves 6.3.1Pressure Flow Hypothesis 6.3.2Evidence for Sucrose Translocation 6.3.1Pressure Flow Hypothesis 6.3.2Evidence for Sucrose Translocation

“Normal” plants are known as Mesophytes.

1.Limit Water Loss 2.Water Storage 3.Water Acquisition

1.Gaseous Exchange 2.Floatation 2. Hydrophytic adaptation