Q: A reaction has $$\Delta H = -100 kJ/$$mol and $$\Delta S = +0.2 kJ/($$mol\cdot K). At $$T = 300 K$$, what is $$\Delta G$$ for the reaction?

$$\Delta G = -100 - (300 \times 0.2) = -160 kJ/$$mol

Question 1

Which of the following statements best distinguishes passive transport from active transport across a biological membrane?

Accepted Answer

Passive transport moves molecules down their concentration gradient without energy input, while active transport moves molecules against their gradient and requires energy.

Question 2

A cell is placed in a solution containing a high concentration of glucose. Which process will most likely allow glucose to enter the cell if the cell membrane is impermeable to glucose?

Accepted Answer

Facilitated diffusion via a glucose transporter protein

Question 3

Which of the following best describes the role of ATP in active transport?

Accepted Answer

ATP donates a phosphate group to the carrier protein, changing its shape and allowing solute transport against the concentration gradient.

Question 4

Which of the following equations correctly represents the relationship between free energy change ($$\Delta G$$), enthalpy change ($$\Delta H$$), temperature ($$T$$), and entropy change ($$\Delta S$$)?

Accepted Answer

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

Question 5

A reaction has $$\Delta H = -100 kJ/$$mol and $$\Delta S = +0.2 kJ/($$mol\cdot K). At $$T = 300 K$$, what is $$\Delta G$$ for the reaction?

Accepted Answer

$$\Delta G = -100 - (300 	imes 0.2) = -160 kJ/$$mol

Question 6

Which of the following is an example of work being done by a cell?

Accepted Answer

Synthesizing a large biomolecule from smaller subunits

Question 7

Which of the following best explains why active transport is necessary for maintaining life in cells, as shown in the 'LIFE/DEATH' diagram?

Accepted Answer

Active transport allows cells to maintain chemical gradients essential for processes like nerve signaling and nutrient uptake.

Question 8

Facilitated diffusion differs from simple diffusion in that facilitated diffusion:

Accepted Answer

Requires specific membrane proteins to transport molecules down their concentration gradient.

Question 9

If a cell's membrane proteins responsible for active transport are inhibited, what is the most likely consequence?

Accepted Answer

The cell will be unable to maintain necessary concentration gradients, leading to loss of vital functions.

Question 10

Which of the following statements about entropy ($$S) is $$correct?

Accepted Answer

Entropy is a measure of system disorder; as entropy increases, the system becomes more disordered and less able to do work.

Question 11

A nerve cell uses facilitated diffusion to allow Na$$^+$$ ions to enter the cell. What triggers the opening of the channel proteins for Na$$^+$$?

Accepted Answer

The influx of Na$$^+$$ causing depolarization, which opens voltage-gated Na$$^+$$ channels

Question 12

Which of the following best describes the direction of solute movement in passive transport?

Accepted Answer

From high concentration to low concentration

Question 13

Which of the following is NOT a characteristic of active transport?

Accepted Answer

It allows solutes to move spontaneously down their concentration gradient.

Question 14

A cell is maintaining a high concentration of potassium ions (K$$^+) $$inside and a low concentration outside. Which process is responsible for this distribution?

Accepted Answer

Active transport via a K$$^+$$ pump

Question 15

Which of the following scenarios would result in a negative $$\Delta G ($$spontaneous reaction)?

Accepted Answer

A reaction with $$\Delta H  0$$

Question 16

Which of the following best explains why the movement of a solute down its concentration gradient is not considered 'work' in the context of cellular processes?

Accepted Answer

Because it happens spontaneously without the need for energy input

Question 17

Which of the following is a real-world example of a chemical gradient doing work in a biological system?

Accepted Answer

The synthesis of ATP by ATP synthase using a proton gradient across the mitochondrial membrane

Question 18

If $$\Delta G \u003e 0$$ for a chemical reaction, which of the following is true?

Accepted Answer

The reaction is nonspontaneous and requires an input of energy.

Cell Membrane Transport and Energy in Biological Systems

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