Lab Practical 2 review fa23

Lab 6: Cell Diffusion

  • Objectives: Review key objectives for understanding cell diffusion.

  • Results: Examine results gathered from the lab experiment on diffusion.

  • Discussion Questions: Explore questions to deepen understanding of lab content.

Part I: Imbibition

  • Definition: Imbibition is the process of water movement into a solid material.

  • Observations: Post-soaking weight changes in peas - did they weigh more or less after one hour of soaking?

Part II: Diffusion

  • Processes Observed:

    • Dye Molecules: The diffusion of dye molecules in a solution.

    • Water Molecules: The movement of water molecules towards equilibrium.

    • Equilibrium: Achieved when molecules become evenly distributed across the space.

Specific Observations

  • Potassium Diffusion:

    • Potassium ions diffuse into the agar, illustrating diffusion principles.

  • Cloudy Salt Ring:

    • Molecules diffuse from cotton balls, creating a cloudy surrounding due to reaction.

Rate of Diffusion

  • Base vs. Acid:

    • Observation: The base (NH4 ion) diffuses faster than the heavier Cl- ion because lighter substances diffuse faster than heavier ones.

  • Solid, Liquid, or Gas:

    • Determine which state diffuses faster based on molecular weight and size.

Control Tube in Diffusion Experiment

  • Types of Beets: Compare the control tube with beet samples (boiled, frozen, chemical added).

  • Effects of Heating, Freezing, and Alcohol: Understand how each treatment affects the integrity of the plasma membrane.

Artificial Cells Experiment

  • Cell Composition:

    • Both cells placed in a beaker - one contained 75% sugar, the other a varied concentration.

    • Water Percentage: Identify water concentration in the bag compared to sugar concentration.

  • Weight and Volume Changes:

    • The bag containing 75% sugar absorbs more water and therefore weight compared to the 1% sugar bag due to osmotic effects.

Movement Mechanism

  • Osmosis:

    • The process by which water moves into the artificial cell, driven by concentration gradients.

Tonicity and Its Effects

  • Tonicity Types:

    • Isotonic: Solute concentration is equal inside and outside the cell.

    • Hypotonic: Solute concentration is lower outside the cell, causing cells to swell.

    • Hypertonic: Solute concentration is higher outside, leading to cell shrinkage.

Lab 7: Enzyme Activity

  • Objectives and Results: Review key objectives and outcomes from the enzyme activity lab.

  • Importance of Enzymes:

    • Enzymes facilitate biological reactions crucial to metabolism.

    • Discuss roles of enzymes in reactions, including rates and transformations.

Tube Observations - Enzyme Activity

  • Tube A:

    • Potential outcomes include enzyme denaturation or inhibition which affects the reaction outcome (solidification vs. liquid).

  • Tube B:

    • The lack of enzyme present leads to solidification, distinguishing enzyme activity.

Lab 8: Photosynthesis

  • Rate of Photosynthesis:

    • Effect of light distance on photosynthesis rate - as distance increases, light intensity and rate decrease.

  • Carbonate Use in Experiment:

    • Sodium carbonate (NaCO3) is used to provide CO2 for the plant's photosynthesis.

  • Measurement Techniques:

    • Rate measured through O2 production and dye movement due to oxygen generation during photosynthesis.

Lab 9: Fermentation

  • Anaerobic Respiration:

    • Key equation for yeast fermentation: C6H12O6

    • Importance of yeast in anaerobic processes outlined through experimenting variables like temperature.

Lab 11: Cell Division

  • Mitosis:

    • Understanding phases: Prophase, Metaphase, Anaphase, Telophase through slide observations.

    • Chromosome Count: Understanding chromosome numbers in fertilized eggs compared to body cells.

  • Meiosis Differences:

    • Mitosis vs Meiosis comparison based on daughter cell production, division cycles, and genetic variability.