Questions and Answers
What is the movement of molecules from areas of higher concentration to areas of lower concentration called?
Simple diffusion
When sugar is mixed with water, equilibrium is reached when?
The dissolved sugar molecules are evenly distributed throughout the solution.
What factors affect the rate of diffusion?
Temperature, size of molecules, and steepness of the concentration gradient.
The molecules in a solid lump of sugar do not move.
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Diffusion is one of the processes whereby materials are exchanged between a cell and its environment.
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What is the process called when water molecules move across the membrane from an area of high concentration to an area of lower concentration?
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What will pass through a cell membrane most easily?
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A red cell placed in a hypertonic medium will ________.
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A 5% urea solution is hypertonic to a 10% urea solution.
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If a cell is placed in an isotonic medium, there will be no net movement of water.
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What does facilitated diffusion require?
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When does facilitated diffusion occur?
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What is facilitated diffusion used to transport?
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Unlike simple diffusion, facilitated diffusion requires energy expenditure by the cell.
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Facilitated diffusion requires a specific transporter for a specific molecule.
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What happens when the acetylcholine receptor sites are not occupied?
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What happens when acetylcholine binds to the receptor sites?
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When the sodium channels open, it causes what to happen?
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The sodium channels in the cell membrane have receptor sites for acetylcholine.
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The sodium channels in the cell membrane have receptor sites for acetylcholine. This channel is formed by a channel protein.
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What does the sodium-potassium pump function to pump?
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What is the source of energy used to power the sodium-potassium pump?
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During one cycle, the sodium-potassium pump binds and moves what?
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The sodium-potassium pump is a trans-membrane protein.
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The binding and release of sodium or potassium ions are due to conformational changes in the protein.
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What are phagocytes not attracted to?
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In phagocytosis, the digested contents are eliminated by what?
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What does a lysosome contain?
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Complement factor C3b coats a bacterium and binds to C3b receptors on phagocytes, making the bacterium more susceptible to being phagocytized.
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A phagosome containing the engulfed bacteria combines with a lysosome containing enzymes to produce a phagolysosome.
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Study Notes
Diffusion and Concentration
- Simple diffusion refers to the movement of molecules from areas of higher concentration to areas of lower concentration.
- When sugar is mixed with water, equilibrium is achieved when sugar molecules are evenly distributed.
- Factors affecting diffusion rate include temperature, size of molecules, and steepness of the concentration gradient.
Properties of Solids and Diffusion
- Molecules in a solid lump of sugar do move, challenging the misconception that they stay still.
- Diffusion is a process for exchanging materials between a cell and its environment.
Osmosis and Cell Membrane Permeability
- Osmosis involves water molecules moving across a membrane from high to low concentration.
- Small nonpolar molecules pass through a cell membrane most easily.
- A red blood cell placed in a hypertonic medium will shrink due to water loss.
Tonicity and Solutions
- True: A 5% urea solution is hypertonic to a 10% urea solution.
- True: There is no net movement of water if a cell is placed in an isotonic medium.
Facilitated Diffusion
- Facilitated diffusion requires carrier proteins to help transport materials.
- This process can occur in either direction based on the concentration gradient of the molecule.
- Facilitated diffusion is primarily used to transport sugars and amino acids.
Energy and Transport Mechanisms
- False: Unlike simple diffusion, facilitated diffusion does not require energy from the cell.
- True: Facilitated diffusion necessitates a specific transporter for each molecule.
Acetylcholine and Sodium Channels
- When acetylcholine receptor sites are not occupied, sodium channels remain closed.
- Binding of acetylcholine to receptors causes sodium channels to open, allowing sodium ions to diffuse into the cell.
- Sodium channels have receptor sites for acetylcholine and are formed by channel proteins.
Sodium-Potassium Pump Functionality
- The sodium-potassium pump functions to pump sodium ions out and potassium ions into the cell, critical for maintaining cell potential.
- The energy for this pump originates from the breakdown of ATP.
- During one cycle, the pump moves 3 Na+ ions out and 2 K+ ions in.
- The pump is a trans-membrane protein, and its binding and release of ions involve conformational changes in the protein.
Phagocytosis and Lysosomes
- Phagocytes are not attracted to lysosomes themselves, instead targeting foreign materials.
- In phagocytosis, digested contents are eliminated through exocytosis.
- Lysosomes contain lysozyme and proteases that digest bacteria.
Immune Response and Phagocytosis
- True: Complement factor C3b enhances the susceptibility of bacteria to phagocytosis by binding to receptors on phagocytes.
- A phagosome containing engulfed bacteria fuses with a lysosome, creating a phagolysosome for digestion.
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Description
Test your knowledge on diffusion, osmosis, and the properties of solids in relation to cellular functions. This quiz covers the principles of molecular movement, factors affecting diffusion rates, and the effects of different solutions on cells. Perfect for biology students wanting to assess their understanding of these key concepts.
