Bio lab chapters 1-5

  • Hypothesis: A tentative, testable explanation for an observation.

  • Prediction: An "If... then..." statement describing the expected outcome if the hypothesis is true.

  • Independent Variable: The factor you manipulate (e.g., Tibia length).

  • Dependent Variable: The factor you measure (e.g., Total height).

  • Controlled Variables: Factors kept constant to ensure a fair test (e.g., same measuring tool).

  • Control Group: A baseline group that does not receive the experimental treatment.

  • Scientific Limits: Not all questions can be answered scientifically. Science only addresses falsifiable questions—those involving phenomena that can be observed and measured. It cannot answer questions of morality, ethics, or the supernatural.

  • Graphing Conclusions: In the Tibia vs. Height lab, a positive correlation (upward trend) usually appears. If the data points cluster around a line showing that taller people have longer tibias, the trend supports the hypothesis that bone length predicts height.

2. Microscopy

a labeled compound light microscope, AI generated

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  • Key Terms:

    • Resolving Power: The ability to distinguish two close points as separate.

    • Parfocal: The ability to switch objectives and keep the specimen nearly in focus.

    • Working Distance: The space between the objective lens and the slide.

    • Field of View: The circular area visible through the eyepiece.

  • Total Magnification: Calculated as Ocular Lens (10x)×Objective Lens.

  • The Image: Images are inverted (upside down and flipped). If you move the slide right, the image appears to move left.

3. Macromolecules

The four categories are Carbohydrates, Lipids, Proteins, and Nucleic Acids.

  • Carbohydrates: Use Glycosidic linkages.

    • Monosaccharide: Glucose (Simple sugar).

    • Disaccharide: Sucrose (Table sugar).

    • Polysaccharide: Starch or Cellulose.

  • Proteins: Made of Amino Acid monomers linked by Peptide bonds.

  • Reagent Testing:

Reagent

Tests For

Positive Color

Negative Color

Benedict’s

Reducing Sugars

Orange/Red

Blue

Lugol’s (Iodine)

Starch

Blue-Black

Yellow-Brown

Biuret

Protein

Violet/Purple

Light Blue

  • Symbiosis: Trichonympha (a protist) lives in a mutualistic relationship with termites. It digests cellulose (wood) for the termite. Under a microscope, it is a flagellated, tear-drop shaped cell. It is a unicellular eukaryote.

4. Cells

  • Domains: Bacteria & Archaea (Prokaryotic); Eukarya (Eukaryotic).

  • Bacteria: Shapes include Cocci (spheres), Bacilli (rods), and Spirilla (spirals).

  • Gram Staining:

    • Gram +: Thick peptidoglycan layer; stains Purple.

    • Gram -: Thin peptidoglycan + LPS outer membrane; stains Pink/Red.

  • Cyanobacteria: Photosynthetic (autotrophic) bacteria. Oscillatoria looks like long filaments; Anabaena looks like beads on a string (often found in Azolla ferns).

  • Organization:

    • Volvox: Colonial (hollow spheres).

    • Scenedesmus: Simple aggregate (usually 4 cells wide).

    • Plant/Animal: Multicellular.

5. Diffusion & Osmosis

  • Definitions:

    • Diffusion: Movement of solutes from high to low concentration.

    • Osmosis: Movement of water across a selectively permeable membrane.

    • Tonicity: The ability of a solution to cause a cell to gain or lose water.

plant and animal cells in hypertonic, isotonic, and hypotonic solutions, AI generated

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  • Environments:

    • Hypotonic (Low salt): Animal cells Lyse (burst); Plant cells become Turgid (normal/firm).

    • Hypertonic (High salt): Animal cells Crenate (shrivel); Plant cells undergo Plasmolysis (membrane pulls away from wall).

  • The "Fake Cell" (Dialysis Tubing): Usually filled with starch/glucose and placed in iodine. If iodine enters, the "cell" turns blue (diffusion of iodine).

  • Potato Experiment: By soaking potato slices in different salt concentrations and measuring weight change, the Isotonic Point is where the line crosses the x-axis on a graph (0% change in mass).