Q: A reaction in a cell has $Q < Keq$. What does this indicate about the direction of the reaction and the sign of $\Delta G$?

The reaction will proceed to the right; $\Delta G < 0$

Q: Which of the following statements about the First Law of Thermodynamics in biological systems is correct?

Cells transform energy from one form to another, but cannot create or destroy it.

Q: Which of the following is TRUE regarding the role of cholesterol in the plasma membrane?

Cholesterol decreases membrane fluidity at high temperatures and increases it at low temperatures.

Q: A cell is actively pumping sodium ions out and potassium ions in, against their concentration gradients. Which type of transport is this, and what is the ratio of ions moved?

Active transport; 3 sodium out, 2 potassium in

Q: Which of the following best explains why living cells must remain far from equilibrium?

At equilibrium, $\Delta G = 0$ and no net work can be performed.

Q: Which of the following is a correct statement about the Second Law of Thermodynamics as it applies to living systems?

Living systems decrease entropy locally but increase the entropy of the universe overall.

Question 1

Which of the following best describes the difference between energy flow and matter flow in the biosphere?

Accepted Answer

Energy flows in one direction, while matter cycles between organisms and the environment.

Question 2

A cell is performing mechanical work by moving vesicles along microtubules. Which type of cellular work is this, and what is the primary energy source?

Accepted Answer

Mechanical work; energy from ATP hydrolysis

Question 3

Which equation correctly represents the change in free energy for a reaction under standard biochemical conditions?

Accepted Answer

$\Delta G^{\circ\prime} = -RT \ln(Keq)$

Question 4

A reaction in a cell has $Q < Keq$. What does this indicate about the direction of the reaction and the sign of $\Delta G$?

Accepted Answer

The reaction will proceed to the right; $\Delta G < 0$

Question 5

Which of the following statements about the First Law of Thermodynamics in biological systems is correct?

Accepted Answer

Cells transform energy from one form to another, but cannot create or destroy it.

Question 6

Which of the following is TRUE regarding the role of cholesterol in the plasma membrane?

Accepted Answer

Cholesterol decreases membrane fluidity at high temperatures and increases it at low temperatures.

Question 7

A cell is actively pumping sodium ions out and potassium ions in, against their concentration gradients. Which type of transport is this, and what is the ratio of ions moved?

Accepted Answer

Active transport; 3 sodium out, 2 potassium in

Question 8

Which of the following best explains why living cells must remain far from equilibrium?

Accepted Answer

At equilibrium, $\Delta G = 0$ and no net work can be performed.

Question 9

Which of the following membrane components is most responsible for the selective permeability of the plasma membrane?

Accepted Answer

Phospholipid bilayer

Question 10

A reaction has $\Delta G > 0$ in the cell. How can the cell drive this reaction forward?

Accepted Answer

By coupling it to an exergonic reaction with $\Delta G < 0$ so that $\Delta G_{total} < 0$

Question 11

Which of the following is a correct statement about the Second Law of Thermodynamics as it applies to living systems?

Accepted Answer

Living systems decrease entropy locally but increase the entropy of the universe overall.

Question 12

Which of the following best describes the amphipathic nature of phospholipids?

Accepted Answer

They have hydrophobic tails and hydrophilic heads.

Question 13

Which type of membrane protein crosses the lipid bilayer as an alpha helix and is involved in signal transduction?

Accepted Answer

Integral transmembrane protein

Question 14

A cell is placed in a hypotonic solution. What will happen to the cell and why?

Accepted Answer

The cell will swell because water enters the cell.

Question 15

Which of the following is TRUE about facilitated diffusion?

Accepted Answer

It uses protein channels or transporters to move molecules down their concentration gradient.

Question 16

Which equation describes the relationship between free energy, enthalpy, and entropy?

Accepted Answer

$\Delta G = \Delta H - T\Delta S$

Question 17

Which of the following is a real-life application of liposomes formed by phospholipids in water?

Accepted Answer

Drug delivery systems that protect drugs from immune destruction

Question 18

Which of the following statements about membrane protein types is correct?

Accepted Answer

Integral membrane proteins are embedded within the lipid bilayer.

Question 19

A mutation in the spectrin protein affects the cell cortex of red blood cells. What is a likely consequence?

Accepted Answer

Anemia and structural changes in red blood cells

Question 20

Which of the following is a correct statement about the effect of unsaturated fatty acids on membrane properties?

Accepted Answer

They decrease the melting point and increase membrane fluidity.

Cellular Bioenergetics and Membrane Structure: Study Guide

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