22 Questions
Which of the following statements accurately describes a concentration gradient?
It arises from the unequal distribution of substances, driving movement from higher to lower concentration.
What is the process by which water moves across a selectively permeable membrane?
Osmosis
In the context of osmosis, which of the following solutions would cause water to move into a cell?
A hypotonic solution
How is concentration typically represented in the context of solutions?
With square brackets around the solute of interest
If a solution is hypertonic compared to another solution, what does this imply about their solute concentrations?
The hypertonic solution has a higher solute concentration.
In the context of osmosis, what happens when two solutions are isotonic?
No net movement of water occurs between the solutions.
In osmosis, which direction does water move?
From a hypotonic solution to a hypertonic solution
What drives the movement of a substance down its concentration gradient?
Imbalance of solutes between two solutions
How is equilibrium defined in the context of concentration gradients?
Equal distribution of substances
Which type of solution has a higher concentration of solutes?
Hypertonic
What happens when two solutions are isotonic?
They will reach equilibrium
How is concentration typically represented when discussing solutions?
[Solute]
Which of the following statements accurately describes the role of turgor pressure in plant cells?
Turgor pressure is the force exerted by the cell wall on the cytoplasm, resulting from water entering the cell via osmosis.
What is the primary function of aquaporins in the context of transmembrane diffusion?
To selectively allow the passage of water molecules across the membrane, while preventing the diffusion of other substances.
In the context of red blood cells, what is the primary mechanism used to maintain an isotonic internal environment?
Active transport of ions across the cell membrane to balance solute concentrations.
Which of the following statements accurately describes the relationship between polarity and size in the context of transmembrane diffusion?
Both polarity and size are important factors that determine the ability of a molecule to diffuse across the phospholipid bilayer.
Consider a plant cell in a hypotonic solution. Which of the following statements accurately describes the resulting effects on the cell?
Water will move into the cell, increasing turgor pressure and causing the cell to become turgid.
Which statement accurately describes the relationship between polarity, size, and transmembrane diffusion?
Polar and small molecules can diffuse through the hydrophobic interior of a phospholipid bilayer, while non-polar and large molecules cannot.
What is the primary mechanism by which red blood cells maintain an isotonic internal environment?
Active transport of ions to balance solute concentrations
In the context of plant cells, what is the primary function of turgor pressure?
To provide structural support and protection to the cell
Which of the following statements accurately describes the process of osmosis across a lipid bilayer?
Water moves through the hydrophobic interior of the bilayer or through aquaporins, while solutes cannot cross the bilayer.
In the context of solutions, what is the primary factor that determines the direction of osmosis?
The concentration gradient of solutes
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).
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.
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