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REVIEW
• If-then statements• How to present statistical results• Figure and Table Captions• Data Interpretation
If-then Statements• If (hypothesis) then (prediction)
• If a cheek cell is to be isotonic, then a hypotonic solution must have ions added to it
• If UV exposure stimulates vitamin D production, then patients with skin cancer will probably have higher levels of vitamin D then other cancer patients
• If a hypotonic solution surrounding cheek cells has ions added to it, then it will move towards isotonicity
• If patients with skin cancer tend to have higher concentrations of vitamin D in their blood than other cancer patients, then sun exposure probably stimulates vitamin D production
Figure & Table Captions• Main information to include in your Figure and table caption:
Describe what the graph shows
– EXAMPLE: This graph shows the percent change in mass in potatoes after being soaked for 15 minutes in different salt water solutions.
• Include any statistical tests (what type of statistical test (if you did a regression analysis then include the R2 value and you don’t need to state the type of statistical test since the reader will know), P-value)
– EXAMPLE: The mass of the potatoes significantly decreased with increasing salt water solutions (R2= 0.85, p<0.0001).
Data Interpretation
• Was your experiment appropriate to address your hypothesis?
• Did you have a large enough sample size? • If your R2 is high that means there is low variability in
your dependent variable which means that you can have a small sample size.
• Were there unexpected errors that occurred that may make your data unreliable?
• A low p-value does NOT necessarily mean that you adequately tested your hypothesis
How do you know if you adequately tested your hypothesis?
Visible Light• Light can travel as a
wave. • Different types of light
have different wavelengths.
• Energy from visible light is used in photosynthesis.• Colors of visible light have wavelengths that vary from 380 nm (violet) to 750 nm (red).
Pigments1. Chlorophyll a
Converts sunlight energy into chemical energy.
2. Chlorophyll b Act as accessory pigment:
absorbs & transfers energy from sun to energy conversion centers of chlorophyll a.
3. Carotenes & Xanthophylls
Act as accessory pigments: absorb & transfer energy from sun to energy conversion centers of chlorophyll a.
Dissipate excess light energy, which can cause cellular damage.
Absorption Spectrum
• Blue Line → Chlorophyll a
• Red Line → Chlorophyll b• Green Line → Carotene• Orange Line → Xanthophyll
Paper Chromatography• Process used to separate compounds
in solution from each another. • Process involves:
– Applying solution with several dissolved compounds onto paper.
– Placing piece of paper in solvent.– Solvent moves up paper & carries each
dissolved compound to different distance.
• The distance that a compound moves up the paper is determined by:– The solubility of the compound in the solvent.– The attraction of the compound to the paper.
Paper Chromatography• Polar Molecules contain Oxygen atoms.• In today’s lab, we are using:
– Polar chromatography paper.
– Nonpolar solvent.
• Why do deciduous trees have leaves that change color in the fall?
Procedure #2 Student Projects!! Work in groups of 1, 2 or 3.• Read Appendix F on Presentations.• Abstracts of past winners found at:
– http://www.colorado.edu/eeb/courses/1230jbasey Best 10 presentation abstracts in the entire
General Biology I Lab will receive 10 bonus points!• Read Appendix E on Abstracts.• I will pick Top 2 Abstracts from my 2 labs. • 10 Points is A LOT!!
Procedure #2 Project Requirements:
1. Must ask a “why” level question.• NOT a “what” level question.
2. Replication is necessary.• Minimum of 3 replicates.
3. Control group is needed.4. Statistical analysis must be used.
Before leaving today, groups must have & verify with me:1. Question2. Hypothesis 3. Prediction4. Experimental Methods