BIOS 1300 Midterm Exam Questions with Correct Answers Latest Update 2025/2026
What is an amphipathic molecule? - Answers A molecule that has both hydrophobic and
hydrophilic regions.
What are phospholipids? - Answers Lipids that form the bilayer of the plasma membrane,
consisting of a hydrophilic head and hydrophobic tails.
What role do glycolipids play in membranes? - Answers They are lipids with one or more sugars
covalently linked, contributing to cell recognition.
What is the structure of the plasma membrane? - Answers A phospholipid bilayer with
embedded proteins, creating a fluid mosaic model.
What does 'fluid mosaic' mean in the context of the plasma membrane? - Answers It refers to
the flexible nature of the membrane and the diverse composition of molecules within it.
What is selective permeability? - Answers The property of the plasma membrane that allows
some substances to pass while restricting others based on size and polarity.
What are integral proteins? - Answers Proteins that are embedded in the membrane and can be
amphipathic, spanning partially or entirely through the membrane.
What distinguishes transmembrane proteins from other integral proteins? - Answers
Transmembrane proteins span the entire membrane, while integral proteins may only partially
penetrate it.
What are peripheral proteins? - Answers Proteins located on the surface of the membrane,
associated with either phospholipids or integral proteins.
What are glycoproteins? - Answers Proteins with sugar chains covalently linked, playing a role in
cell recognition and identity.
What is the function of channel proteins? - Answers They form passageways for specific ions or
molecules to pass through the membrane.
What are aquaporins? - Answers Channel proteins that facilitate the rapid transport of water
across the plasma membrane.
How do carrier proteins function? - Answers They help small polar molecules cross the
membrane by changing shape to transport them.
What are cell adhesion proteins? - Answers Proteins that link cells together or anchor them to
the extracellular matrix.
What role do receptor proteins play in cellular signaling? - Answers They bind to signaling
molecules (ligands) and relay messages to the cell's interior.
, What are second messengers in cellular signaling? - Answers Small molecules that continue the
signal transduction inside the cell, such as cAMP and Ca++.
What is a concentration gradient? - Answers A region along which the concentration of a
substance changes, which can affect membrane permeability.
What is the electrochemical gradient? - Answers The difference in charge and chemical
concentration across a membrane, influencing ion movement.
What is membrane potential? - Answers The electrical charge difference across a membrane,
typically measured in millivolts (mV).
What is the resting membrane potential of a typical cell? - Answers Approximately -70 to -90 mV.
What is diffusion? - Answers The process where molecules spread out to fill space, moving
from high concentration to low concentration.
What is osmosis? - Answers The movement of water from high water concentration to low
water concentration, or from low solute concentration to high solute concentration.
What is reverse osmosis? - Answers A method used to purify water by forcing it through a
semipermeable membrane.
What are the three types of tonicity? - Answers Hypertonic, isotonic, and hypotonic.
What happens to cells in a hypotonic solution? - Answers Cells may swell and potentially burst
due to water influx.
What happens to cells in a hypertonic solution? - Answers Cells undergo crenation, shrinking
due to water loss.
What is passive transport? - Answers The movement of substances across membranes without
the need for energy.
What is facilitated diffusion? - Answers A type of passive transport where substances need help
from channel or carrier proteins to pass through the membrane.
What is active transport? - Answers The movement of substances against their concentration
gradient, requiring energy (ATP).
What is the Na+/K+ pump? - Answers An active transport mechanism that pumps 3 sodium ions
out of the cell and 2 potassium ions into the cell.
What is membrane potential? - Answers The electrical charge difference across a membrane,
typically measured in millivolts (mV).
What is cotransport? - Answers The simultaneous transport of two or more solutes, usually
What is an amphipathic molecule? - Answers A molecule that has both hydrophobic and
hydrophilic regions.
What are phospholipids? - Answers Lipids that form the bilayer of the plasma membrane,
consisting of a hydrophilic head and hydrophobic tails.
What role do glycolipids play in membranes? - Answers They are lipids with one or more sugars
covalently linked, contributing to cell recognition.
What is the structure of the plasma membrane? - Answers A phospholipid bilayer with
embedded proteins, creating a fluid mosaic model.
What does 'fluid mosaic' mean in the context of the plasma membrane? - Answers It refers to
the flexible nature of the membrane and the diverse composition of molecules within it.
What is selective permeability? - Answers The property of the plasma membrane that allows
some substances to pass while restricting others based on size and polarity.
What are integral proteins? - Answers Proteins that are embedded in the membrane and can be
amphipathic, spanning partially or entirely through the membrane.
What distinguishes transmembrane proteins from other integral proteins? - Answers
Transmembrane proteins span the entire membrane, while integral proteins may only partially
penetrate it.
What are peripheral proteins? - Answers Proteins located on the surface of the membrane,
associated with either phospholipids or integral proteins.
What are glycoproteins? - Answers Proteins with sugar chains covalently linked, playing a role in
cell recognition and identity.
What is the function of channel proteins? - Answers They form passageways for specific ions or
molecules to pass through the membrane.
What are aquaporins? - Answers Channel proteins that facilitate the rapid transport of water
across the plasma membrane.
How do carrier proteins function? - Answers They help small polar molecules cross the
membrane by changing shape to transport them.
What are cell adhesion proteins? - Answers Proteins that link cells together or anchor them to
the extracellular matrix.
What role do receptor proteins play in cellular signaling? - Answers They bind to signaling
molecules (ligands) and relay messages to the cell's interior.
, What are second messengers in cellular signaling? - Answers Small molecules that continue the
signal transduction inside the cell, such as cAMP and Ca++.
What is a concentration gradient? - Answers A region along which the concentration of a
substance changes, which can affect membrane permeability.
What is the electrochemical gradient? - Answers The difference in charge and chemical
concentration across a membrane, influencing ion movement.
What is membrane potential? - Answers The electrical charge difference across a membrane,
typically measured in millivolts (mV).
What is the resting membrane potential of a typical cell? - Answers Approximately -70 to -90 mV.
What is diffusion? - Answers The process where molecules spread out to fill space, moving
from high concentration to low concentration.
What is osmosis? - Answers The movement of water from high water concentration to low
water concentration, or from low solute concentration to high solute concentration.
What is reverse osmosis? - Answers A method used to purify water by forcing it through a
semipermeable membrane.
What are the three types of tonicity? - Answers Hypertonic, isotonic, and hypotonic.
What happens to cells in a hypotonic solution? - Answers Cells may swell and potentially burst
due to water influx.
What happens to cells in a hypertonic solution? - Answers Cells undergo crenation, shrinking
due to water loss.
What is passive transport? - Answers The movement of substances across membranes without
the need for energy.
What is facilitated diffusion? - Answers A type of passive transport where substances need help
from channel or carrier proteins to pass through the membrane.
What is active transport? - Answers The movement of substances against their concentration
gradient, requiring energy (ATP).
What is the Na+/K+ pump? - Answers An active transport mechanism that pumps 3 sodium ions
out of the cell and 2 potassium ions into the cell.
What is membrane potential? - Answers The electrical charge difference across a membrane,
typically measured in millivolts (mV).
What is cotransport? - Answers The simultaneous transport of two or more solutes, usually
