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Lab exam #1

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Terms in this set (24)

  • What is diffusion?

    Diffusion is the movement of molecules from an area of higher concentration to an area of lower concentration due to random molecular motion.

  • Define osmosis.

    Osmosis is the diffusion of water across a selectively permeable membrane.

  • Name three factors that affect the rate of diffusion.

    Molecule size, concentration gradient, and temperature affect diffusion rate.

  • How does molecule size affect diffusion rate?

    Smaller molecules diffuse faster than larger molecules.

  • What is the effect of concentration gradient on diffusion?

    A greater concentration gradient increases the rate of diffusion.

  • How does temperature influence diffusion?

    Higher temperatures increase molecular motion, thus increasing diffusion rate.

  • Give an example of diffusion in the human body.

    Oxygen and carbon dioxide exchange in the lungs occurs by diffusion.

  • What is an acid in terms of hydrogen ion concentration?

    An acid is a substance that increases the concentration of hydrogen ions (H+) in solution.

  • Define a base in biochemical terms.

    A base is a substance that decreases hydrogen ion concentration, often by providing hydroxide ions (OH-).

  • How is pH defined mathematically?

    pH is defined as \(-\log[H_3O^+]\), the negative logarithm of hydronium ion concentration.

  • What is the typical pH of human blood?

    Blood has a typical pH of about 7.4, which is slightly basic.

  • What pH range is gastric juice typically?

    Gastric juice has a very acidic pH, around 1 to 2.

  • What is the pH of pure water?

    Pure water has a neutral pH of 7.

  • How does pH affect enzyme activity?

    Each enzyme has an optimal pH range; extreme pH values can denature enzymes and reduce their activity.

  • Give an example of enzymes with different optimal pH values.

    Pepsin works best at pH 2, while amylase works best at pH 7.

  • What is an independent variable in an experiment?

    The independent variable is the variable manipulated by the experimenter.

  • Define dependent variable.

    The dependent variable is the variable measured or observed in an experiment.

  • What is a control variable?

    A control variable is kept constant to ensure a fair test.

  • What is the purpose of a control group?

    The control group does not receive the experimental treatment and is used for comparison.

  • In a study of enzyme activity at different pH levels, what is the independent variable?

    pH is the independent variable.

  • In the same enzyme study, what is the dependent variable?

    Enzyme activity is the dependent variable.

  • What does the x-axis usually represent in a graph?

    The x-axis usually represents the independent variable.

  • What does the y-axis usually represent in a graph?

    The y-axis usually represents the dependent variable.

  • What patterns should you look for when interpreting graphs?

    Look for trends such as increases, decreases, or plateaus.