AP Biology
ASFA. Spring. 2010
R. Reardon, Instructor
Names:
AP Laboratory 9: Whole Plant Transpiration.
Procedure:
1) As a class (with advice from your instructor) decide how you are going to set
up your experimental conditions (Control, Arid, High Light, Humid, and Other, if
plants are available).
2) Obtain two plants, remove blooms (flowers), mark the plant with your group
name and wrap the entire root ball (and small plastic pot in a plastic bag, snug it
up the stem with string (wrap string in glad cling wrap, and weigh on days for an
entire week. Record your data in your data sheets.
3) A group will be responsible for the following, the control (ambient
conditions) another group will be responsible for arid plants, another group will
be responsible for arid plants, another group will be responsible for high light
plants, another group will be responsible for humid plants, another group will be
responsible for plants in the dark (or a treatment of your choosing)
4) If your plant(s) blooms, pinch the blooms off and be sure any leaves or blooms
that fall off are put in the center of the plant and weighed each day so as not to
represent water loss.
5) Write a set of null and alternate hypotheses about these experiments.
6) Complete and experimental design diagram for this experiment (we’ll do this
as a class).
7) Discuss your predictions for the experiment as a class.
Results:
1) Determine the % change in mass of each plant for each day, and for the entire
week, and graph your group’s data in Graph 9.1 and the class averages in
Graph 9.2.
Analysis:
1) Answer questions in your lab packet. Make sure Mr. Reardon discusses the
questions with you before you begin writing your answers.
Extensions:
1) Will be available depending on the how the week progresses. Won’t be
available. We are hyper-extended as it is. Don’t worry though, I worked with
some students on Saturday who skipped Chapters 16, 17, 20 and all associated
labs. Mercy (Ain’t gonna happen.)
AP Lab 9_Whole Plant Transpiration. Analysis Questions.
1. Calculate the rate (% change in mass Monday-Friday) for each of the treatments.
Room: (Control): _____________________________________________________
Hi Light: ____________________________________________________________
Arid: _______________________________________________________________
Humid: _____________________________________________________________
Darkness: ___________________________________________________________
Other (____________): ________________________________________________
2. Explain why each of the conditions causes an increase (or decrease) in transpiration
compared to the control.
Condition Effect_________________ Explanation of Effect_________________________
Hi Lite
Arid
Humid
Dark
Other
3. Explain the role of water potential in the movement of water from the soil through the
plant and into the air.
4. What is the advantage of closed stomata to a plant when water is in short supply?
What the disadvantages of closed stomata when water is in short supply?
asfa. ap biology.
spring. 2010.
name:________________
AP Lab 9_Whole Plant Transpiration. Final Question.
Disregard question 5 on the other Analysis Question Packet. Answer these questions
instead.
1. Using the data provided, determine the average temperature (in °C) and the average
relative humidity for each of the four environments.
Hi light: _____________
_________________
High Humidity: _______________ ________________
Arid (Fan): _________________ _________________
Control: __________________
_________________
2. What biome do each of these conditions mimic?
Hi light: _____________
High Humidity: _______________
Arid (Fan): _________________
Control: __________________
3. Based on what you learned from your field investigations, your research of various
biomes and what you know about the “cost and benefits” of adaptations, (natural
selection often selects for “compromises”); describe two to three physiological
adaptations and two to three physical adaptations that plants posses to survive in each
of these biomes. Think about this, how do plants in the rain forest survive when
conditions are ideal for other plants. Conversely, how do plants survive in stressful
environments? Answers to these questions don’t comprise a complete answer, but
should get you thinking about plant structures and functions.