Suck It Up!
Understanding photosynthesis through
quantitative analysis
Regional SI vignette by
BIOLOGY-MATH GROUP
Barbara Kunkel, John Majors, Eleanor Pardini
Washington University in St. Louis
Rachelle Spell and Lynn Zimmerman
Emory University
With thanks to our facilitator Peggy Brickman!
Context
• Introductory Biology, 100 freshmen
• Background: Students will have already been
exposed to
– biomolecules (e.g. carbohydrates  cellulose).
– cellular respiration
– Basic graphing and data analysis skills
(in/dependent variables, types of graphs, etc.)
Overall Learning Goals
• Quantitative literacy skills: Develop
quantitative skills to interpret biological data
• Biology content example = Photosynthesis:
Apply relationship of carbon fixation and plant
biomass to idea of forests serving as carbon
sinks
Quantitative Literacy Learning
Objectives for Course
1. Perform simple manipulations of numerical
data and express data in graphical form
2. Describe and interpret graphs
3. Use numerical evidence to formulate and test
hypotheses
4. Present scientific arguments based on
numerical evidence
Speth et al. 2010 CBE-Life Science Ed.
http://www.youtube.com/watch?v=WbQAxYqC0JE&feature=related
Clicker question
A small acorn grows into a large oak tree. Where
does most of the biomass (weight) of the oak tree
come from?
A. From the natural growth of the tree
B. From carbon dioxide in the air and water in the
soil
C. From water and nutrients that the tree absorbs
through its roots
D. From sunlight that the tree uses for food
Clicker question
A small acorn grows into a large oak tree. Where
does most of the biomass (weight) of the oak tree
come from?
A. From the natural growth of the tree
B. From carbon dioxide in the air and water in the
soil
C. From water and nutrients that the tree absorbs
through its roots chosen by most HARVARD
GRADUATES (see video on Blackboard)
D. From sunlight that the tree uses for food
✔
✗
Mini-lecture on photosynthesis
6 CO2 + 12 H2O + light energy  C6H12O6 + 6 H2O + 6 O2
Cellulose
How could you measure rate of
photosynthesis?
6 CO2 + 12 H2O + light energy  C6H12O6 + 6 H2O + 6 O2
Amount of CO2 in chamber
Before
After
In Class Graphing Activity
1. Talk with your group to decide what type
of graph you should use for this data.
Clicker question
What type of graph would you use to display this data?
Pie chart
Line graph
Bar graph
Scatter plot
Clicker question
What type of graph would you use to display this data?
Pie chart
Line graph
BEST
Bar graph
Scatter plot
In Class Graphing Activity- 5 minutes
2. Label the axes.
3. Draw the graph.
Ambient CO2
concentration
(ppm)
100
200
300
400
600
800
Mean CO2
assimilation
(mol/m2/second)
50
80
100
110
120
125
In Class Graphing Activity- Sample of
Useful Graph
Sample Group Graphs
How do you describe the relationship?
A. As the CO2 level increases, photosynthetic
rate increases
B. As the CO2 level increases, photosynthetic
rate decreases
C. As the photosynthetic rate increases, the CO2
level increases
D. As the photosynthetic rate increases, the CO2
level decreases
How do you describe the relationship?
✔
A. As the CO2 level increases, photosynthetic
rate increases
B. As the CO2 level increases, photosynthetic
rate decreases
C. As the photosynthetic rate increases, the CO2
level increases
D. As the photosynthetic rate increases, the CO2
level decreases
Homework: Keeling Curve
Activities with Keeling Curve
• Class activities or homework as needed for your course
1. Groups plot subsets (n=8) of atmospheric CO2 (Mauna
Loa) over time
–
Trend lines, variance, sample size
2. Examine long term and seasonal trends in Mauna Loa
data
–
Long term = fossil fuel; seasonal variation = photosynthesis
3. Examine trends at three sites: Mauna Loa Mauna Loa,
Barrow, and South Pole.
–
Variation in amplitude of seasonal variation among sites with
different amounts of vegetation
Summative assessment –
see handout
1. skill analysis
2. content analysis
Tips, tricks, and resources
•
•
•
Photosynthesis figures: Plant physiology textbook
Quantitative literacy problem sets: Intro statistics textbook
Personal carbon footprint calculator
–
•
Thinking like a scientist resources on Photosynthesis
–
•
http://www.nature.org/greenliving/carboncalculator/index.htm
BioDQC.org
Quantitative literacy resources at Project-based Applied Learning
website (Brickman)
–
Pal.uga.org
• Scripps CO2 Center
– http://scrippsco2.ucsd.edu/
• Carbon Dioxide Information Analysis Center
– http://cdiac.ornl.gov/
Learning Objective
Assessment
Active learning
Low Order/
High Order
Perform simple
manipulations of numerical
data and express data in
graphical form
1. Clicker ? Graph type
choice
2. Graphing activity
3. Exam ? on plotting
graph
1. Clicker ? Acorn to oak
2. Graphing activity and
clicker ?s
3. Homework on Mauna
Loa
High
Describe and interpret
graphs
1. Clicker ? CO2/biomass
relationship
2. Mauna Loa graph
homework
3. Exam ? on carbon
fixation and global
warming
1. Clicker ? CO2/biomass
relationship
2. Mauna Loa graph
homework
High
Relate carbon fixation to
biomass
1. Clicker ? Acorn to oak
2. Graphing activity
hypothesis creation
3. Exam ? on carbon
fixation and global
warming
1. Clicker ? Acorn to oak
2. Graphing activity
hypothesis creation
2. Mauna Loa graph
homework
High
Diversity: Audio, visual, kinesthetic learning
Homework: Keeling Curve
•Charles David Keeling - Scripps Institution of
Oceanography, University of California, San
Diego, from 1956 until his death in 2005.
Charles David Keeling
Manometer
CO2 extractor
Amount of CO2
in chamber
Amount of CO2 in chamber
Difference
Time