Scientific Method and Stats
Which measure of central tendency is best for data with extreme outliers? Why?
Median, because it is not distorted by extreme values.
Explain how hydrogen bonds lead to water’s high heat of vaporization and why this is critical for homeostasis.
Energy must break H-bonds before molecules escape as vapor, allowing organisms to dissipate large amounts of heat via evaporative cooling
Draw a simple glucose molecule (ring form) and label carbon numbers 1–6. (you do not have to write in all the hydroxyl groups)
Hexagonal ring with, numbering clockwise starting from the furthest right carbon.
Name the building blocks of fats.
Glycerol + 3 fatty acids.
Describe how peptide bonds form.
Dehydration synthesis between carboxyl group of one amino acid and amino group of another.
Give an example of a negative control for an experiment testing if caffeine increases heart rate.
Provide subjects with water (no expected effect on heart rate).
Draw three water molecules showing all hydrogen bonds between them. Label δ+ and δ− charges.
O atoms δ−, H atoms δ+, dashed hydrogen bonds connecting O–H between different molecules.
Compare α- and β-glycosidic linkages and their effect on digestibility.
α-linkages (starch) are easily hydrolyzed by enzymes, β-linkages (cellulose) resist digestion except by specialized microbes
Draw a phospholipid labeling the hydrophilic head and hydrophobic tails.
Head (phosphate + glycerol) polar, tails (fatty acids) nonpolar
Explain how disulfide bridges stabilize proteins.
Covalent S–S bonds form between cysteine side chains, reinforcing tertiary structure.
Critique this hypothesis: “Plants grow better when music is played.” Rewrite it to be testable and measurable.
Critique: “better” is vague; must specify a measurable variable. Rewrite: “Exposure to classical music for 2 hours per day increases mean plant height compared to no music.” Requires some sort of qualitative/quantitative data collection.
Evaluate this claim: “Adding detergent to water increases its surface tension.”
False — detergents disrupt hydrogen bonds, reducing cohesion and surface tension.
Explain how polysaccharide branching affects glycogen’s function in animals.
Highly branched glycogen allows rapid release of glucose when energy is needed quickly.
Predict the effect of a missing phosphate group on nucleic acid assembly.
No phosphodiester bond forms, preventing chain elongation.
Predict the effect of high fever on enzyme structure.
Heat denatures enzyme, disrupting active site and halting function.
Two treatments have the same mean but one has a much higher standard deviation. What does this suggest about experimental reliability?
The treatment with higher SD has more variability, suggesting less consistency and potentially uncontrolled variables influencing results
Explain how water’s polarity allows ionic compounds like NaCl to dissociate, then apply this concept to nutrient cycling in soil. Hint: Nutrients include potassium ions and polyatomic ions like phosphates and nitrates.
Water’s partial charges surround ions, pulling them apart. In soil, this allows nitrate, phosphate, and potassium ions to stay dissolved and available to plants.
Draw a dehydration reaction linking two glucose molecules and label the glycosidic bond.
C1–C4 bond forms, water molecule is released.
Draw a cross-section of a cell membrane labeling phospholipids, proteins, and cholesterol.
Bilayer with heads outward, tails inward, proteins spanning or embedded, cholesterol between tails for fluidity.
Draw a generic amino acid labeling amino group, carboxyl group, and R group.
Central carbon with NH2, COOH, H, and R side chain attached.
Explain how double-blind studies minimize researcher bias.
Neither the participants nor experimenters know which group receives treatment, reducing unconscious influence on results or interpretation.
Describe the molecular events during sweating that allow humans to cool themselves, linking to thermodynamic principles.
Heat energy from skin breaks H-bonds between water molecules, increasing kinetic energy until evaporation; high heat of vaporization carries away large amounts of heat energy.
Predict what happens if glycogen phosphorylase (the enzyme for breaking down glycogen).
Blood glucose drops during fasting because glycogen cannot break down to release glucose. One effect this leads to is a metabolic shift toward lipolysis: body relies more heavily on fatty acids for energy.
Predict what would happen to membrane permeability if saturated fatty acid content increased.
Membrane becomes less fluid and more rigid, reducing permeability.
Explain how a change in primary structure can alter tertiary structure.
Different R-groups alter folding interactions (H-bonds, hydrophobic effects), potentially changing protein shape and function.