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Questions and Answers
What is the primary characteristic of diffusion?
What is the primary characteristic of diffusion?
- It can only occur for small molecules.
- It involves random motion of molecules. (correct)
- It moves molecules from low to high concentration.
- It requires energy input from the cell.
Which of the following molecules can utilize simple diffusion to pass through the cell membrane?
Which of the following molecules can utilize simple diffusion to pass through the cell membrane?
- Amino acids
- Glucose
- Oxygen (correct)
- Proteins
How does osmosis differ from simple diffusion?
How does osmosis differ from simple diffusion?
- Osmosis cannot occur across a semipermeable membrane.
- Osmosis involves the movement of solute molecules.
- Osmosis specifically involves the movement of water. (correct)
- Osmosis requires energy to occur.
What role do protein channels play in facilitated diffusion?
What role do protein channels play in facilitated diffusion?
What is the primary function of aquaporin proteins?
What is the primary function of aquaporin proteins?
What is true about the energy requirements of active transport?
What is true about the energy requirements of active transport?
What is the primary outcome of maintaining cell hydration through osmosis?
What is the primary outcome of maintaining cell hydration through osmosis?
What does the term 'selective permeability' refer to in the context of cell membranes?
What does the term 'selective permeability' refer to in the context of cell membranes?
Study Notes
Diffusion
- Molecules move from high concentration areas to low concentration areas without energy input.
- Essential for gas exchange, nutrient transport, and waste removal in cells.
- Molecules capable of simple diffusion include water, oxygen, carbon dioxide, ethanol, and urea.
- These molecules pass through the cell membrane along the concentration gradient.
Osmosis
- Defined as the movement of water molecules across a semipermeable membrane from lower solute concentration to higher solute concentration.
- Critical for maintaining cell hydration and regulating osmotic pressure.
- Affects cell volume by altering water content.
Active Transport
- Requires energy to move ions or molecules against their concentration gradient.
- Vital for functions such as nerve signaling, muscle contraction, and nutrient uptake.
Transport Proteins
- Specific molecules move across the cell membrane with the help of transport proteins.
- Used for larger molecules that cannot easily penetrate the lipid bilayer.
- Maintains selective permeability of the cell membrane for controlled molecule movement.
- Protein channels facilitate rapid transport and exhibit selectivity based on size.
Aquaporins
- Aquaporin proteins discovered by Peter Agre in 1992, awarded the Nobel Prize in Chemistry in 2003.
- These proteins significantly enhance the transport of water across cell membranes.
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Description
Explore the fundamental process of diffusion in cells. This quiz covers the movement of molecules from areas of high concentration to low concentration, highlighting its importance in gas exchange, nutrient absorption, and waste removal. Test your understanding of how diffusion operates without energy input.
