30 Questions
Which type of molecules can pass through the phospholipid layers of the plasma membrane via simple diffusion?
Nonpolar molecules
What type of proteins are involved in the simple diffusion of ions through the membrane?
Channel proteins
Which process involves carrier proteins that undergo a conformational change to release molecules on the other side of the membrane?
Facilitated diffusion
Which molecules can pass through the lipid portion of the membrane easily?
Uncharged lipid-soluble molecules
Gas exchange for O2 into cells and CO2 out of cells due to concentration gradients mainly occurs in which part of the body?
Lungs
What specific channels allow water to pass through the plasma membrane in a process called osmosis?
Aquaporins
Which statement best describes the movement of water during osmosis?
Water moves from the area of low solute concentration to the area of high solute concentration.
What is the relationship between the solute concentration of a solution and its osmotic pressure?
Osmotic pressure increases as solute concentration increases.
What is the osmotic pressure of pure water?
Pure water has an osmotic pressure of zero.
What is the primary force that drives the process of osmosis?
Concentration gradient of solute molecules.
What is the purpose of osmotic pressure?
Osmotic pressure is used to describe the force required to stop osmosis.
Which of the following best describes the role of a semi-permeable membrane in the process of osmosis?
The semi-permeable membrane allows the passage of solvent molecules but not solute molecules.
What is the main function of osmoreceptors in the hypothalamus?
To stimulate the release of antidiuretic hormone
What is the main effect of a lower plasma osmolality on the osmoreceptors in the hypothalamus?
It increases the excretion of water in the urine
What is the primary role of carrier proteins in the plasma membrane?
To allow the diffusion of large or polar molecules across the membrane
Which of the following is a characteristic of carrier proteins in the plasma membrane?
They are specific to a given molecule
How does facilitated diffusion differ from simple diffusion?
Facilitated diffusion is limited by the number of carrier proteins, while simple diffusion is not
What is the primary difference between osmoreceptors and carrier proteins in the plasma membrane?
Osmoreceptors detect changes in osmolality, while carrier proteins transport molecules across the membrane
What is the primary purpose of the Na+/K+ pump?
To maintain the concentration gradient of sodium and potassium across the cell membrane
Which of the following is NOT a step in the Na+/K+ pump mechanism?
The pump releases 3 Na+ to the outside of the cell
What is the key difference between primary and secondary active transport?
Primary active transport uses ATP directly, while secondary active transport uses the sodium gradient
What is the role of the sodium gradient in secondary active transport?
The sodium gradient provides the energy needed to move other molecules against their concentration gradient
What is the primary requirement for the fusion of a vesicle with the plasma membrane?
Requires ATP
What is the purpose of the shape changes in the Na+/K+ pump mechanism?
To facilitate the binding and unbinding of the sodium and potassium ions
What is the main mechanism by which large molecules, such as cholesterol, are transported into the cell?
Receptor-mediated endocytosis
What is the primary factor that contributes to the difference in charge on each side of the plasma membrane?
All of the above
What is the role of ATP hydrolysis in the Na+/K+ pump mechanism?
To provide the energy needed to move the sodium and potassium ions
What is the term used to describe the difference in charge on each side of the plasma membrane?
Membrane potential
Which of the following is true about the membrane potential?
The membrane potential is caused by the permeability of the membrane.
What is the relationship between the membrane potential and the charge difference across the plasma membrane?
The membrane potential is directly proportional to the charge difference across the plasma membrane.
Test your knowledge on the different types of passive transport mechanisms in cells, including simple diffusion of lipid-soluble molecules, ions through membrane channels, and facilitated diffusion of organic molecules. Learn about the processes involved in moving substances across the cell membrane.
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