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Questions and Answers
Which factor does NOT influence the rate of diffusion?
Which factor does NOT influence the rate of diffusion?
What is the primary result of osmosis occurring in plant cells?
What is the primary result of osmosis occurring in plant cells?
What defines a hypertonic solution?
What defines a hypertonic solution?
What is essential for the function of osmosis in animal cells?
What is essential for the function of osmosis in animal cells?
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Which statement incorrectly describes diffusion?
Which statement incorrectly describes diffusion?
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How does an increase in temperature affect diffusion rates?
How does an increase in temperature affect diffusion rates?
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Which of the following solutions would be considered isotonic for red blood cells?
Which of the following solutions would be considered isotonic for red blood cells?
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What primarily regulates the movement of water in animal cells?
What primarily regulates the movement of water in animal cells?
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Which statement is true regarding osmosis?
Which statement is true regarding osmosis?
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What effect does a hypotonic solution have on animal cells?
What effect does a hypotonic solution have on animal cells?
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Study Notes
Diffusion
- Diffusion is the movement of particles (solutes) or different molecules from high concentration to low concentration.
- Diffusion stops when the concentration gradient is zero (equilibrium).
- Diffusion rate is the diffusion through a unit of time (the change in the number of diffusing molecules inside).
Methods of Crossing the Cell Membrane
- Active transport: Movement of substances from a region of lower concentration to a region of higher concentration. This requires energy from cellular respiration. It moves against the concentration gradient.
- Passive transport: Movement of substances from a region of higher concentration to a region of lower concentration. This does not require energy. It moves with the concentration gradient.
Factors affecting Diffusion
- Temperature: Higher temperature leads to faster diffusion.
- Concentration gradient: Higher gradient leads to faster diffusion.
- Molecular weight: Lower molecular weight leads to faster diffusion.
- Pressure: Higher pressure facilitates faster diffusion.
- Time: More time, faster diffusion.
Importance of Diffusion
- Gaseous exchange: In respiration and photosynthesis, plants and animals use oxygen and carbon dioxide diffuses in/out.
- Excretion of waste: Waste diffuses out of tissues, then transported by the circulatory system to excretory organs.
- Absorption of digested food: Digested food diffuses into the bloodstream. Excess minerals, salts, and vitamins are removed from the bloodstream through diffusion as well.
Experiments Aims
- Discuss the importance and functions of the cell membrane
- Understand the factors that affect the rate of diffusion of materials to the cell membrane.
Osmosis
- Osmosis is the movement of solvent molecules through a semipermeable membrane from a region of lower solute concentration to a region of higher solute concentration. It equalizes the concentrations on both sides.
Osmotic Solutions
- Isotonic: Same solute concentration inside and outside the cell (e.g., 0.9% NaCl for red blood cells).
- Hypertonic: Higher solute concentration outside the cell than inside.
- Hypotonic: Lower solute concentration outside the cell than inside.
Osmosis in Plant Cells
- Plant cells have a rigid cell wall that maintains turgor pressure during osmosis.
- Osmosis causes water uptake in plant cells, maintaining cell rigidity and shape.
Osmosis in Animal Cells
- Cell membranes regulate water and solute movement for cellular processes and stability.
- Osmosis ensures cells are properly hydrated and functioning optimally.
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Description
Explore the concepts of diffusion and methods of crossing the cell membrane in this quiz. Understand the differences between active and passive transport, and the factors that affect diffusion rates. Test your knowledge on how concentration gradients and temperature influence molecular movement.
