BIOL 2160 EXAM REVIEW GUIDE 2026
COMPLETE PRACTICE QUESTIONS AND
ANSWERS
●● What does semi-permeable mean in the context of the plasma
membrane? Answer: It allows certain substances to pass while blocking
others, similar to a screen door.
●● Why can small and nonpolar molecules freely diffuse across the cell
membrane? Answer: Because they are similar in nature to the nonpolar
tails of phospholipids, allowing them to dissolve easily.
●● What types of molecules cannot cross the cell membrane without
assistance? Answer: Large, charged, or polar molecules require carrier
proteins to cross the membrane.
●● What is passive transport? Answer: Movement across the membrane
that does not require energy, occurring from areas of high concentration
to low concentration.
●● What is the relationship between solute concentration and energy in
passive transport? Answer: Higher solute concentration results in higher
energy, driving the movement of solutes from high to low concentration.
, ●● What is active transport? Answer: Transport that requires energy to
move substances from low to high concentration, often using a pump
like Na/K ATPase.
●● What is the role of ATP in active transport? Answer: ATP provides
the energy needed to move ions against their concentration gradients.
●● What is the typical resting membrane potential of most cells?
Answer: -70 millivolts (mV).
●● What is membrane potential? Answer: The difference in electrical
potential or voltage across the plasma membrane, comparing inside to
outside.
●● What does the chemical force in membrane potential refer to?
Answer: The concentration gradient, indicating how much of a
substance is present inside versus outside the cell.
●● What is the effect of electrical force on ions in the membrane
potential? Answer: It affects charged molecules, pushing cations out and
drawing anions in based on the membrane's charge.
●● What is the electrochemical force? Answer: The combined effect of
chemical and electrical forces on ion movement across the membrane.
COMPLETE PRACTICE QUESTIONS AND
ANSWERS
●● What does semi-permeable mean in the context of the plasma
membrane? Answer: It allows certain substances to pass while blocking
others, similar to a screen door.
●● Why can small and nonpolar molecules freely diffuse across the cell
membrane? Answer: Because they are similar in nature to the nonpolar
tails of phospholipids, allowing them to dissolve easily.
●● What types of molecules cannot cross the cell membrane without
assistance? Answer: Large, charged, or polar molecules require carrier
proteins to cross the membrane.
●● What is passive transport? Answer: Movement across the membrane
that does not require energy, occurring from areas of high concentration
to low concentration.
●● What is the relationship between solute concentration and energy in
passive transport? Answer: Higher solute concentration results in higher
energy, driving the movement of solutes from high to low concentration.
, ●● What is active transport? Answer: Transport that requires energy to
move substances from low to high concentration, often using a pump
like Na/K ATPase.
●● What is the role of ATP in active transport? Answer: ATP provides
the energy needed to move ions against their concentration gradients.
●● What is the typical resting membrane potential of most cells?
Answer: -70 millivolts (mV).
●● What is membrane potential? Answer: The difference in electrical
potential or voltage across the plasma membrane, comparing inside to
outside.
●● What does the chemical force in membrane potential refer to?
Answer: The concentration gradient, indicating how much of a
substance is present inside versus outside the cell.
●● What is the effect of electrical force on ions in the membrane
potential? Answer: It affects charged molecules, pushing cations out and
drawing anions in based on the membrane's charge.
●● What is the electrochemical force? Answer: The combined effect of
chemical and electrical forces on ion movement across the membrane.
