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Questions and Answers
What happens to a cell placed in a solution with a higher water potential than its cytoplasm?
What happens to a cell placed in a solution with a higher water potential than its cytoplasm?
Which of the following statements about osmosis is true?
Which of the following statements about osmosis is true?
What factors affect the rate of diffusion?
What factors affect the rate of diffusion?
What is the primary requirement for active transport to occur?
What is the primary requirement for active transport to occur?
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What happens in an isotonic solution regarding water movement?
What happens in an isotonic solution regarding water movement?
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How does temperature affect diffusion?
How does temperature affect diffusion?
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Which process is primarily utilized for the uptake of nutrients in the digestive system?
Which process is primarily utilized for the uptake of nutrients in the digestive system?
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In terms of water potential, how are solutions with differing solute concentrations categorized?
In terms of water potential, how are solutions with differing solute concentrations categorized?
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Study Notes
Osmosis
- Osmosis is the movement of water molecules from a region of high water potential to a region of low water potential across a partially permeable membrane.
- Water potential is a measure of the tendency of water molecules to move from one area to another. Pure water has the highest water potential, assigned a value of 0 kPa.
- Solute concentration affects water potential. Solutions with a higher solute concentration have a lower water potential than pure water.
- Water moves to equalize the water potential across the membrane.
- If a cell is placed in a solution with a higher water potential than the cell's cytoplasm, water moves into the cell, causing it to swell or burst (lysis).
- If a cell is placed in a solution with a lower water potential than the cell's cytoplasm, water moves out of the cell, causing it to shrink or become plasmolysed.
- A solution with the same water potential as the cell's cytoplasm is called an isotonic solution. No net water movement occurs in this case.
Diffusion
- Diffusion is the net movement of particles from a region of high concentration to a region of low concentration.
- Particles move randomly, leading to a net movement from high to low concentration.
- Factors affecting diffusion rate include:
- Concentration gradient: A larger difference in concentration increases diffusion speed.
- Temperature: Higher temperatures increase particle kinetic energy, accelerating diffusion.
- Surface area: A larger surface area allows more particles to diffuse simultaneously.
- Distance: Shorter distances lead to faster diffusion.
- Diffusion is a passive process, requiring no energy input.
Active Transport
- Active transport moves particles across a cell membrane from a region of low concentration to a region of high concentration.
- This process requires energy, typically ATP.
- Active transport utilizes protein channels/pumps embedded in the cell membrane to facilitate specific molecule movement.
- Active transport is crucial for:
- Nutrient uptake from the digestive system.
- Waste removal from the blood.
- Maintaining concentration gradients of essential substances like sodium and potassium ions within the cell.
- Mineral absorption against concentration gradients.
- Active transport should be distinguished from facilitated diffusion, which uses protein channels but doesn't require energy.
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Description
Test your knowledge on osmosis and water potential with this engaging quiz. Understand the movement of water molecules across membranes, the impact of solute concentration, and how cells respond to different solutions. Perfect for biology students!
