58 Questions
What is the primary difference in electrical properties between the plasma and cytoplasm of a cell?
Plasma has more sodium ions, while cytoplasm has more potassium ions
What are the two common characteristics of the plasma and cytoplasm in terms of particle concentrations?
Electroneutrality and equal osmotic pressures.
The cell membrane is least permeable to:
Ions
How do carrier proteins facilitate transport across the cell membrane?
Through a conformational change that transports molecules, requiring metabolic energy
Aquaporins primarily facilitate the transport of:
Water
Which statement best describes Na-K leak channels?
They are always open, allowing easier passage of potassium ions due to their smaller hydration shell.
The selectivity of protein channels in a cell membrane is primarily determined by:
The size, shape, and charge distribution of the channel's inner surface.
Which molecules pass through the lipid bilayer of the cell membrane most easily?
Small nonpolar and weakly polar molecules
Which of the following best describes the role of transport proteins in the cell membrane?
They facilitate the passage of water and ions through the membrane
Aquaporins are specialized for transporting:
Water molecules
Which of the following statements is true about protein channels in cell membranes?
Some are constantly open, while others open and close due to external stimulation
Na-K leak channels are characterized by:
Being continuously open and allowing easy passage of potassium ions
Which statement correctly describes the structure of a typical cell membrane?
A double layer of lipids with embedded proteins
The primary function of cholesterol in the cell membrane is to:
Stabilize the membrane at various temperatures
What is the significance of the cell membrane's 'fluid mosaic model'?
Suggests that the membrane components are fluid and can move laterally
What is the primary function of voltage-dependent protein channels in cells?
They regulate the opening and closing based on membrane potential.
Facilitated diffusion differs from regular diffusion in that it:
Involves transport proteins in the process.
Osmosis in cells refers to:
The net diffusion of water through semipermeable membranes.
The Na-K pump is an example of:
Active transport.
Ligand-gated channels in the cell membrane open in response to:
The binding of specific molecules.
Facilitated diffusion is characterized by:
Presence of transport proteins and movement from higher to lower concentration.
Osmosis can be best described as:
Net diffusion of water through semipermeable membranes.
In active transport, how are substances moved across a cell membrane?
From an area of lower concentration to higher concentration, using ATP.
Which factor primarily determines the direction of net diffusion of molecules in a solution?
The concentration gradient of the molecules.
The osmotic pressure of a solution is directly proportional to:
The molar concentration of dissolved particles.
In the context of membrane transport, 'active transport' is best described as:
The transport of molecules against their concentration gradient using energy.
What is the role of the Na-K pump in cellular function?
It helps maintain the cell’s membrane potential and regulates cell volume.
Which statement accurately describes osmotic swelling and shrinkage of cells?
All of the above.
The Nernst equation is used to calculate:
The membrane potential based on ion concentration gradients.
Which process best describes the movement of glucose into a cell?
Facilitated diffusion.
What is the primary role of the Na-K pump in maintaining cell volume?
Regulating osmotic pressure.
In secondary active transport, the energy to transport molecules is derived from:
The gradient created by primary active transport
Which statement correctly describes osmotic pressures in solutions?
Isoosmotic solutions have equal osmotic pressures.
How does the concentration of ions inside and outside a cell primarily affect the membrane potential?
The ratio of ion concentrations inside and outside the cell directly influences the membrane potential.
The Goldman equation is used to calculate:
The membrane potential considering multiple ion types.
What is a primary function of secondary active transport in cells?
To transport molecules using the energy stored in ion gradients.
Which of the following best describes the role of ion channels in the cell membrane?
They facilitate the passive transport of specific ions.
In the context of cell membrane transport, what does 'selectivity' refer to?
The preference of transport proteins for specific ions or molecules
Which statement best describes the effect of membrane potential on the movement of ions across the cell membrane?
Membrane potential influences the directional movement of ions based on their charge.
The process of active transport in cells is characterized by:
Transport of substances against their concentration gradient using cellular energy.
Osmotic pressure in cells is most directly affected by:
The concentration of non-permeable solutes.
Which of the following is true about facilitated diffusion?
It involves transport proteins and moves substances from higher to lower concentration.
In secondary active transport, what is the relationship between the transport of sodium and the co-transported substance?
Sodium and the co-transported substance move in the same direction across the membrane.
Which statement is true about the Na-K pump's role in nerve signal conduction?
It maintains the concentration gradients essential for action potential propagation.
In the context of membrane transport, what does 'saturation kinetics' refer to?
The rate of transport does not increase with increased substrate concentration.
Which factor primarily influences the movement of ions due to the electric field across a cell membrane?
The intensity of the electric field across the membrane.
The concept of 'electrochemical equilibrium' in cells refers to:
A state where there is no net movement of ions across the membrane.
What does the 'reflection coefficient' in membrane transport indicate?
The proportion of a solute's osmotic pressure contributing to net water flow.
What effect does the Na-K pump have on the concentration of ions inside the cell?
It decreases sodium ion concentration and increases potassium ion concentration.
Secondary active transport is distinguished by:
Utilizing energy from ion gradients created by primary active transport.
In facilitated diffusion, what role do transport proteins play?
They provide a passage through the membrane for specific molecules.
The concept of 'osmotic pressure' is best explained as:
The pressure required to prevent the flow of water across a semipermeable membrane.
What is the primary factor determining the direction of water movement in osmosis?
The concentration of solutes that cannot cross the membrane.
In terms of membrane transport, what is the significance of the 'reflection coefficient'?
It represents the degree of solute permeability through the membrane.
Which ions primarily contribute to the resting membrane potential in neurons?
Potassium and sodium ions.
What is the primary purpose of the Na-K pump in cellular activity?
Maintaining concentration gradients of sodium and potassium ions.
Which process describes the movement of water from an area of low solute concentration to an area of high solute concentration?
Osmosis.
The term 'electrogenic transport' refers to:
Transport processes that contribute to the generation of a membrane potential.
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