Biology Lab Modules Study Guide Flashcards

Core Concepts and Definitions:
- Scientific Method: An organized, repeatable approach to answer questions about the natural world while minimizing bias.
- Hypothesis ( $H_a$ ): An educated guess or testable statement predicting a specific outcome or difference between variables.
- Null Hypothesis ( $H_0$ ): A statement proposing that there is no significant difference or effect between treatment groups.
- Independent (Treatment) Variable: The factor intentionally manipulated by the experimenter (e.g., type of nutrient fed to yeast).
- Dependent (Response) Variable: The factor measured to determine the effect of the independent variable (e.g., volume of $\text{CO}_2$ gas produced).
- Controls: Standard baseline conditions used for direct comparison that exclude the independent variable (e.g., using water instead of food solutions).
- Replication: Repeated trials under identical conditions to ensure reliability and validity.
Review Questions and Key Answers:
- Observations: Specific, detailed observations are better suited for scientific investigations than broad ones.
- Yeast Nutrition: Yeast metabolizes carbohydrates more efficiently than proteins, producing $\text{CO}_2$ gas as a byproduct.

Core Concepts and Definitions:
- Acid: A molecule or ion that acts as a proton donor ( $\text{H}^+$ donor). Solutions have a $\text{pH} < 7$ and taste sour.
- Base (Alkali): A molecule or ion that acts as a hydroxide donor ( $\text{OH}^-$ donor) or proton acceptor. Solutions have a $\text{pH} > 7$ and taste bitter.
- Neutralization: The reaction between an acid and a base to form water and a salt: $\text{H}^+ + \text{OH}^- \rightarrow \text{H}_2\text{O}$
- Buffer: A system (usually a weak acid and its conjugate base) that resists drastic changes in $\text{pH}$ when small amounts of acid or base are added.
- Biological Importance: Buffers maintain $\text{pH}$ homeostasis in biological fluids. For example, the human blood buffer system keeps blood $\text{pH}$ within $\text{pH}$ $7.35\text{--}7.45$ : $\text{CO}_2 + \text{H}_2\text{O} \rightleftharpoons \text{H}_2\text{CO}_3 \rightleftharpoons \text{H}^+ + \text{HCO}_3^-$
Summary Table of Lab Results:
- Activity 2 (Antacids Titration):
  - Subject / Test: Antacids Titration.
  - Key Finding / Winner: Alka-Seltzer.
  - Reason: Required the most drops of acid ( $100+$ drops) because it contained more $\text{OH}^-$ / neutralizing base.
- Activity 3 (Buffering Capacity):
  - Subject / Test: Buffering Capacity.
  - Key Finding / Winner: $0.1\,\text{M}$ Phosphate Buffer.
  - Reason: Maintained a stable $\text{pH}$ compared to water, which had no buffering capacity.

Antacids titration and buffering capacity lab results

Core Concepts and Definitions:
- Diffusion: Movement of particles from an area of higher concentration to lower concentration without energy input (passive transport).
- Osmosis: Net movement of water molecules across a semi-permeable membrane from an area of higher water potential (hypotonic) to lower water potential (hypertonic).
- Hypotonic Solution: Lower solute concentration than the cell; water moves into the cell (cells swell).
- Isotonic Solution: Equal solute concentration; no net movement of water.
- Hypertonic Solution: Higher solute concentration than the cell; water moves out of the cell (cells shrink).
Lab Indicators and Permeability Summary:
- Iodine ( $\text{I}$ ): Tests for starch (turns dark blue/black).
- Phenolphthalein: Tests for bases (turns pink in basic solutions).
- Silver Nitrate ( $\text{AgNO}_3$ ): Tests for chloride ions ( $\text{Cl}^-$ ), forming a white precipitate ( $\text{AgCl}$ ).
Dialysis Membrane Permeability Results:
- Small Molecules / Ions ( $\text{Cl}^-$ , $\text{Na}^+$ , $\text{OH}^-$ , Iodine):
  - Crossed Dialysis Membrane: Yes.
  - Factor Allowing/Blocking Movement: Small molecular size allows passage through dialysis tubing pores.
- Starch:
  - Crossed Dialysis Membrane: No.
  - Factor Allowing/Blocking Movement: Large molecular size (macromolecule) prevents passage.

Dialysis membrane permeability for small molecules and ions

Dialysis membrane impermeability to starch

Crucial Comparison:
- Dialysis tubing selects only by size.
- Real biological membranes are selectively permeable phospholipid bilayers that block charged ions regardless of size without specific channel/pump proteins.

Summary of Macromolecules:
- Carbohydrates:
  - Monomer Unit: Glucose subunits / Monosaccharides.
  - Key Functions: Short-term energy, structural components.
  - Examples: Glucose, Starch, Glycogen.
- Lipids:
  - Monomer Unit: Fatty acids & Glycerol.
  - Key Functions: Long-term energy storage, cell membranes.
  - Examples: Fats, oils, phospholipids.
- Proteins:
  - Monomer Unit: Amino acids.
  - Key Functions: Enzymes, structural components, transport.
  - Examples: Enzymes, Keratin, Collagen, Whey.
- Nucleic Acids:
  - Monomer Unit: Nucleotides.
  - Key Functions: Genetic information storage and transmission.
  - Examples: DNA, RNA.

Macromolecules classification, monomer units, functions, and examples

Chemical Reagents and Positive Tests:
- Benedict's Reagent:
  - Target Macromolecule: Simple / Reducing Sugars.
  - Negative Result Color: Blue.
  - Positive Result Color: Green, Yellow, Orange, or Red-Brown.
- Iodine Test:
  - Target Macromolecule: Starch.
  - Negative Result Color: Yellow-Brown / Amber.
  - Positive Result Color: Dark Blue-Black.
- Biuret Reagent:
  - Target Macromolecule: Proteins / Peptide Bonds.
  - Negative Result Color: Light Blue.
  - Positive Result Color: Lavender / Violet / Purple.

Chemical reagents and positive test results for macromolecules

Formulas and Calculations:
- Total Magnification Formula: $\text{Total Magnification} = \text{Ocular Lens Magnification} \times \text{Objective Lens Magnification}$
- Scanning Power ( $4\text{X}$ Objective): $10\text{X} \times 4\text{X} = 40\text{X}\,\text{total magnification}$
- Low Power ( $10\text{X}$ Objective): $10\text{X} \times 10\text{X} = 100\text{X}\,\text{total magnification}$
- High Power ( $40\text{X}$ Objective): $10\text{X} \times 40\text{X} = 400\text{X}\,\text{total magnification}$
Rules of Microscopy Trends:
- As magnification increases, the following four parameters change:
  1. Field of Vision (FOV): Decreases (you see a smaller area in higher detail).
  2. Depth of Field: Decreases (thinner slice of specimen is in sharp focus).
  3. Brightness / Light Intensity: Decreases (requires iris diaphragm adjustment).
  4. Working Distance: Decreases (objective lens sits physically closer to slide).
Image Orientation and Stage Movement:
- Compound microscopes invert (turn upside down) and reverse (flip left-to-right) the specimen image.
- Directional Stage Movement:
  - To move an image Right $\rightarrow$ move stage Left.
  - To move an image Up $\rightarrow$ move stage Down.