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Questions and Answers
According to Fick's Law of Diffusion, if the concentration difference across a membrane doubles while the membrane thickness remains constant, how is the rate of diffusion affected?
According to Fick's Law of Diffusion, if the concentration difference across a membrane doubles while the membrane thickness remains constant, how is the rate of diffusion affected?
- The rate of diffusion quadruples.
- The rate of diffusion remains unchanged.
- The rate of diffusion doubles. (correct)
- The rate of diffusion is halved.
Which of the following factors would decrease the rate of simple diffusion across a cell membrane?
Which of the following factors would decrease the rate of simple diffusion across a cell membrane?
- Increased cross-sectional area of the membrane.
- Increased temperature.
- Decreased membrane thickness.
- Decreased concentration gradient. (correct)
Why is maintaining a concentration gradient crucial for cells?
Why is maintaining a concentration gradient crucial for cells?
- To prevent any movement of molecules across the cell membrane.
- To allow all molecules inside and outside of cells to reach equilibrium.
- To increase the energy expenditure of the cell.
- To facilitate the net movement of essential molecules into the cell and waste products out. (correct)
What distinguishes passive transport from active transport across a cell membrane?
What distinguishes passive transport from active transport across a cell membrane?
How does diffusion contribute to maintaining a cell's physiological activities?
How does diffusion contribute to maintaining a cell's physiological activities?
A scientist observes that a particular molecule is moving across a cell membrane from an area of low concentration to an area of high concentration. Which transport mechanism is most likely responsible for this movement?
A scientist observes that a particular molecule is moving across a cell membrane from an area of low concentration to an area of high concentration. Which transport mechanism is most likely responsible for this movement?
In a scenario where the concentration of a solute is higher inside a cell than outside, which process will initially occur to reach diffusional equilibrium, assuming the membrane is permeable to the solute?
In a scenario where the concentration of a solute is higher inside a cell than outside, which process will initially occur to reach diffusional equilibrium, assuming the membrane is permeable to the solute?
A researcher is studying the transport of a small, nonpolar molecule across a cell membrane. They find that the rate of transport is directly proportional to the concentration gradient of the molecule. Which transport mechanism is most likely involved?
A researcher is studying the transport of a small, nonpolar molecule across a cell membrane. They find that the rate of transport is directly proportional to the concentration gradient of the molecule. Which transport mechanism is most likely involved?
Flashcards
Simple Diffusion
Simple Diffusion
Movement of molecules from high to low concentration areas until equilibrium is reached.
Passive Transport
Passive Transport
Transport across a membrane along a concentration gradient, without energy expenditure by the cell.
Concentration Gradient
Concentration Gradient
The difference in concentration of a substance between two areas.
Random Movement
Random Movement
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Diffusional Equilibrium
Diffusional Equilibrium
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Fick's Law of Diffusion
Fick's Law of Diffusion
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Downhill Movement
Downhill Movement
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Cell necessities
Cell necessities
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Study Notes
- Substances are transported across the cell membrane through various mechanisms.
Passive Transport
- Substances are transported along the gradient without energy expenditure during passive transport.
- Physical factors such as concentration gradient, electrical gradient, and pressure gradient influence it.
- It is also called downhill movement because the transport of substances occurs along the concentration gradient.
- Diffusion and osmosis are the passive transport mechanisms that operate at the cell membrane level.
Simple Diffusion
- Atoms or molecules are transported from one place to another due to random movement.
- Molecules, whether dissolved or undissolved, are at constant random movement, except at absolute zero temperature.
- Molecules collide with each other and strike the cell membrane frequently.
- The probability of striking the cell membrane will be higher on the side of the membrane with higher molecule concentrations.
- There is a net flux of molecules from areas of high concentration to areas of low concentration through a permeable membrane.
- Diffusional equilibrium occurs when the concentration of molecules is equal, and the net movement of molecules ceases.
- Fick's law of diffusion states that the rate of diffusion (J) is directly proportional to the concentration difference (C1 - C2) and cross-sectional area (A) and inversely proportional to the membrane thickness (T).
- Diffusion through the cell membrane is divided into simple diffusion and facilitated diffusion.
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Description
Explore passive transport mechanisms across the cell membrane, focusing on diffusion and osmosis. Understand how concentration gradients influence the movement of substances without energy expenditure. Learn about the random movement of molecules and their impact on cell membrane transport.
