Biology Lab Modules Study Guide Flashcards

Vocabulary flashcards covering core concepts, terminology, formulas, and results across all five biology lab modules.

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 Variable

The factor intentionally manipulated by the experimenter (e.g., type of nutrient fed to yeast).

Dependent Variable

The factor measured to determine the effect of the independent variable (e.g., volume of $\text{CO}_2$ gas produced).

Control

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.

Yeast Carbohydrate Metabolism

Yeast metabolizes carbohydrates more efficiently than proteins, producing $\text{CO}_2$ gas as a byproduct.

Acid

A molecule or ion that acts as a proton donor ($\text{H}^+$ donor), producing solutions with $\text{pH} < 7$ that taste sour.

Base (Alkali)

A molecule or ion that acts as a hydroxide donor ($\text{OH}^-$ donor) or proton acceptor, producing solutions with $\text{pH} > 7$ that 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.

Human Blood Buffer System

The physiological buffer system represented by $\text{CO}_2 + \text{H}_2\text{O} \rightleftharpoons \text{H}_2\text{CO}_3 \rightleftharpoons \text{H}^+ + \text{HCO}_3^-$ that maintains blood $\text{pH}$ within $7.35\text{--}7.45$.

Antacids Titration Result

Alka-Seltzer was the top performer, requiring the most drops of acid ($100+$ drops) because it contained more $\text{-OH}$ / neutralizing base.

Buffering Capacity Result

The $0.1\,\text{M}$ Phosphate Buffer maintained a stable $\text{pH}$ compared to water, which had no buffering capacity.

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

A solution with a lower solute concentration than the cell, causing water to move into the cell so that cells swell.

Hypertonic Solution

A solution with a higher solute concentration than the cell, causing water to move out of the cell so that cells shrink.

Isotonic Solution

A solution with equal solute concentration relative to the cell, resulting in no net movement of water.

Iodine Indicator

A reagent that tests for starch, turning dark blue/black in a positive test.

Phenolphthalein

A chemical indicator that tests for bases, turning pink in basic solutions.

Silver Nitrate ($\text{AgNO}_3$)

A chemical reagent that tests for chloride ions ($\text{Cl}^-$), forming a white precipitate of $\text{AgCl}$.

Dialysis Tubing Permeability

Allows passage of small molecules and ions ($\text{Cl}^-$, $\text{Na}^+$, $\text{OH}^-$, Iodine) due to small size, but blocks large macromolecules like starch.

Dialysis Tubing vs. Biological Membranes

Dialysis tubing selects solely by molecular size, whereas real biological membranes are selectively permeable phospholipid bilayers that block charged ions regardless of size without specific channel or pump proteins.

Carbohydrates

A macromolecule group composed of glucose subunits / monosaccharides used for short-term energy and structural components (e.g., glucose, starch, glycogen).

Lipids

A macromolecule group composed of fatty acids and glycerol used for long-term energy storage and cell membranes (e.g., fats, oils, phospholipids).

Proteins

A macromolecule group composed of amino acids functioning as enzymes, structural components, and transport (e.g., enzymes, keratin, collagen, whey).

Nucleic Acids

A macromolecule group composed of nucleotides responsible for genetic information storage and transmission (e.g., DNA, RNA).

Benedict's Reagent

Reagent targeting simple / reducing sugars; negative result color is blue, and positive result color is green, yellow, orange, or red-brown.

Iodine Test

Test targeting starch; negative result color is yellow-brown / amber, and positive result color is dark blue-black.

Biuret Reagent

Reagent targeting proteins / peptide bonds; negative result color is light blue, and positive result color is lavender / violet / purple.

Total Magnification Formula

$$\text{Total Magnification} = \text{Ocular Lens Magnification} \times \text{Objective Lens Magnification}$$

Scanning Power Magnification

A $4\text{X}$ objective lens combined with a $10\text{X}$ ocular lens ($10\text{X} \times 4\text{X}$) yields $40\text{X}$ total magnification.

Low Power Magnification

A $10\text{X}$ objective lens combined with a $10\text{X}$ ocular lens ($10\text{X} \times 10\text{X}$) yields $100\text{X}$ total magnification.

High Power Magnification

A $40\text{X}$ objective lens combined with a $10\text{X}$ ocular lens ($10\text{X} \times 40\text{X}$) yields $400\text{X}$ total magnification.

Field of Vision (FOV) Trend

As magnification increases, field of vision decreases (a smaller area is viewed in higher detail).

Depth of Field Trend

As magnification increases, depth of field decreases (a thinner slice of specimen is in sharp focus).

Brightness Trend in Microscopy

As magnification increases, brightness / light intensity decreases, requiring adjustment of the iris diaphragm.

Working Distance Trend

As magnification increases, working distance decreases as the objective lens sits physically closer to the slide.

Image Orientation in Compound Microscopes

Compound microscopes invert (turn upside down) and reverse (flip left-to-right) the specimen image.

Microscope Stage Movement Rules

To move an image right, move the stage left; to move an image up, move the stage down.