TRANSPIRATION AP LAB WRITE-UP GUIDELINES
Due Fri, 12/11 or Thurs, 12/10 by 3:30 for +5!
Title
I. Introduction
 Brief explanation of transpiration
 Purpose of Parts A, B
II. Materials & Methods
 Description of procedure followed in Part A
o Revised procedure available on my web page if you can’t find yours
 Description of procedure followed in Part B
 For a complete listing of materials and methods, see lab protocol titled, “Transpiration”
III. Data
 Part A
 Plant Mass Data Table
 Data Table showing % Change in Mass
 Leaf Surface Area Calculation for Each Plant
o Total Mass of Leaves
o Mass of 1 cm2 leaf section
o Calculate leaf surface area using instructions found on lab protocol
 Calculate water loss in mL/m2 for your plants using your data (1 gram water = 1 mL water)
 Class Data will be posted
 Calculate and record the Class Average % Change Per Day for all four set-ups. Construct a data table to
record this information.
 Construct a graph to show Class Average % Change Per Day for all four set-ups.
 Part B
 Hypothesis with justification
 Colored, titled, labeled drawing of Dianthus stomata following guidelines for biological drawings
 Calculation for area of field of view
 Data table
IV. Data Analysis
 Perform the following analysis to determine the quality of the class data for the Average Cumulative Water Loss
(mL/m2) for each set-up..
 Show your work!
o Class Mean for each set-up
 Average Cumulative Water Loss Class Mean = __Sum of All Values___
# of Values
o Standard Deviation in the Class Data for each set-up
 The standard deviation is a means of determining the spread for a given data set. We expect
~68% of the data to be within 1 SD of the mean, ~95% of the data within 2 SD, and ~99.7% of the
data within 3 SD.
 Subtract the mean from each value.
 Square each difference.
 Sum all the resulting squares.
 Divide the sum of the squares by (# of Values – 1)
 Take the square root of this number.
V. Questions – Answer questions 2 – 6 in complete sentences.
1. Calculate the average rate of water loss per day for each set-up using the class mean for average cumulative water
loss.
2. Compare the results of each variable tested to the control. Include a brief explanation of the observed effect for each
variable. Relate your findings to water potential.
3. Summarize the steps of the Light Reaction, including the location in a eukaryotic cell and the importance of water to the
reaction.
4. Explain how water first moves into the root. Describe the two possible pathways for water movement into the root to the
xylem.
5. Discuss the importance of transpiration … would it be advantageous for a plant to eliminate transpiration? Explain.
6. Although closed stomata minimize water loss in dry conditions, it also increases the possibility of photorespiration. What
is photorespiration and why it is harmful to plants?
VI. Conclusion
 Re-address purpose for Part A, B
 Re-address hypothesis for Part A, B
 Discuss results of Data Analysis for Part A
 Error Analysis for Part A only
Academic Pledge