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Questions and Answers
Which of the following statements accurately describes a concentration gradient?
Which of the following statements accurately describes a concentration gradient?
What is the process by which water moves across a selectively permeable membrane?
What is the process by which water moves across a selectively permeable membrane?
In the context of osmosis, which of the following solutions would cause water to move into a cell?
In the context of osmosis, which of the following solutions would cause water to move into a cell?
How is concentration typically represented in the context of solutions?
How is concentration typically represented in the context of solutions?
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If a solution is hypertonic compared to another solution, what does this imply about their solute concentrations?
If a solution is hypertonic compared to another solution, what does this imply about their solute concentrations?
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In the context of osmosis, what happens when two solutions are isotonic?
In the context of osmosis, what happens when two solutions are isotonic?
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In osmosis, which direction does water move?
In osmosis, which direction does water move?
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What drives the movement of a substance down its concentration gradient?
What drives the movement of a substance down its concentration gradient?
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How is equilibrium defined in the context of concentration gradients?
How is equilibrium defined in the context of concentration gradients?
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Which type of solution has a higher concentration of solutes?
Which type of solution has a higher concentration of solutes?
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What happens when two solutions are isotonic?
What happens when two solutions are isotonic?
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How is concentration typically represented when discussing solutions?
How is concentration typically represented when discussing solutions?
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Which of the following statements accurately describes the role of turgor pressure in plant cells?
Which of the following statements accurately describes the role of turgor pressure in plant cells?
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What is the primary function of aquaporins in the context of transmembrane diffusion?
What is the primary function of aquaporins in the context of transmembrane diffusion?
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In the context of red blood cells, what is the primary mechanism used to maintain an isotonic internal environment?
In the context of red blood cells, what is the primary mechanism used to maintain an isotonic internal environment?
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Which of the following statements accurately describes the relationship between polarity and size in the context of transmembrane diffusion?
Which of the following statements accurately describes the relationship between polarity and size in the context of transmembrane diffusion?
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Consider a plant cell in a hypotonic solution. Which of the following statements accurately describes the resulting effects on the cell?
Consider a plant cell in a hypotonic solution. Which of the following statements accurately describes the resulting effects on the cell?
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Which statement accurately describes the relationship between polarity, size, and transmembrane diffusion?
Which statement accurately describes the relationship between polarity, size, and transmembrane diffusion?
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What is the primary mechanism by which red blood cells maintain an isotonic internal environment?
What is the primary mechanism by which red blood cells maintain an isotonic internal environment?
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In the context of plant cells, what is the primary function of turgor pressure?
In the context of plant cells, what is the primary function of turgor pressure?
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Which of the following statements accurately describes the process of osmosis across a lipid bilayer?
Which of the following statements accurately describes the process of osmosis across a lipid bilayer?
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In the context of solutions, what is the primary factor that determines the direction of osmosis?
In the context of solutions, what is the primary factor that determines the direction of osmosis?
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Study Notes
Concentration Gradients
- A concentration gradient occurs when there is an unequal distribution of substances (e.g., ions, glucose molecules) in a cell or across a cell membrane.
- This imbalance of solutes between two solutions drives the movement of a substance from a region of higher concentration to a region of lower concentration.
- Equilibrium is reached when there is no longer a concentration gradient.
Osmosis
- Osmosis is the passive transport of water across a selectively permeable membrane.
- Water diffuses from a region of higher water concentration (lower solute concentration) to a region of lower water concentration (higher solute concentration).
- Concentration refers to the amount of a substance in a defined space (amount/volume).
Hypertonic and Hypotonic Solutions
- A hypertonic solution has a higher concentration of solutes.
- A hypotonic solution has a lower concentration of solutes.
- Solutions are isotonic if they have the same concentrations of solutes.
- In osmosis, water moves from a hypotonic solution to a hypertonic solution.
Transmembrane Diffusion
- The most important parameters that govern transmembrane diffusion are polarity and size.
- Water is polar, but also small, allowing it to pass through the hydrophobic interior of a phospholipid bilayer.
Cell Shape and Osmosis
- Osmosis can affect cell shape.
- Red blood cells use active transport of ions to keep the internal environment of the cell isotonic to the external environment.
- Cell shape and size in red blood cells change based on the solute concentration surrounding the cells.
Cell Walls and Turgor Pressure
- The cell wall provides structural support and protection.
- Turgor pressure within the cell occurs when water moves into the cell through osmosis.
- Water can move across a lipid bilayer via simple diffusion (osmosis) or via facilitated transport through water-selective channels (aquaporins).
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Description
Learn about concentration gradients, the movement of substances across membranes due to uneven distributions, and how osmosis allows the passive transport of water. Explore the concept of equilibrium in terms of solute concentrations.