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