1. http://www. phschool. com/science/biology_place/labbench/lab9/xylem

2. Daily Warm-up Monday, April 21st
What processes help move water up a tree? HW: -Read 42.4 Turn in: -Nothing

3. AP Lab 11: Transpiration What is transpiration?
What do you know about transpiration?

4. Transpiration
Evaporation of water from aerial parts of plants (not roots)
Relies on hydrogen bonding of water molecules and the processes of cohesion and adhesion
Water enters a plant through the root hairs, passes through the tissues of the root into the xylem, and travels up through the xylem vessels into the leaves
Done by water potential (potential energy of water molecules). Water always moves from an area of high to low potential. Moevemnt is facilitated by osmosis, root pressure, and adhesion and cohesion of water molecules.
Minerals are actively transported into the root. Accumulate and decrease the water potential. Water moves in by osmosis. Moves up xylem short ways due to root pressure. Upward pull due to transpiration. Due to cohesion and adhesion of water molecules.
Transpiration begins with evaporation of water through the stomates. Moist air in these spaces have higher potential than those outside, causing evaporation. The moisture in the air spaces replaced by water from adjacent mesophyll cells by osmosis. Exerts a pull on the column of water molecules existing in the xylem all the way from the leaves to the roots.

5. What causes different rates of transpiration?
Number of leaves
Number of stomata
Size of the leaf
Presence of cuticle
Light supply
Temperature
Relative humidity
Wind
Water supply

6. Adaptations for Reducing Water Loss
Leaf structure
Different photosynthesis: CAM plants
Cuticle

7. Today’s Lab Working in groups
Each group will receive one type of plant but must subject the plants to 4 conditions
Wind (fan)
Light (lamp)
Room temperature (away from any drafts)
Humidity (put within a bag that is misted with water)
Will record each day’s mass in table at the beginning of class for remainder of week
Demonstration

8. Steps Receive plant type, break into 4 separate plants
Place plant’s roots in bag of water with mL of water. Tie the bag tightly so that no air is able to escape. Weigh plant and record in table. Each person needs to make a table and record the group’s data.
Set in proper conditions: fan, room temperature, humidity (bag placed over rest of plant), and light
DEMO this

9. Daily Warm-up Monday, April 28th
What type of graph might you use to display the change in % mass for each of the five days? HW: -Transpiration lab due 5/10 Turn in: -Nothing

10. Lab Notebook Title: Transpiration Lab Brief introduction
Hypothesis- inquiry lab worksheet
Methods (no materials required)
Table
Graph- line graph- one line for each treatment showing change in % mass each day
Results- what did you find?
Conclusion- why did you find what you did. Make sure to explain findings and say whether or not hypothesis is SUPPORTED. Include potential errors and future research.
Questions from transpiration question sheet