Q: A reaction has $$\Delta H = -20 kJ/$$mol and $$\Delta S = +0.05 kJ/($$mol\cdot K)$$. At T = 300$ K, what is $$\Delta G$ and is the reaction spontaneous?

$$\Delta G = -20 - (300 \times 0.05) = -20 - 15 = -35 kJ/$$mol; the reaction is spontaneous.

Question 1

Which of the following best describes the role of catabolic pathways in cellular metabolism?

Accepted Answer

They break down complex molecules into simpler ones, releasing energy that the cell can use for work.

Question 2

During cellular respiration, glucose is broken down to carbon dioxide and water. Which statement about this process is correct?

Accepted Answer

It is a catabolic, exergonic pathway that releases free energy, some of which is captured as ATP.

Question 3

Which equation correctly represents the relationship between free energy, enthalpy, entropy, and temperature in a biological system?

Accepted Answer

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

Question 4

A reaction has $$\Delta H = -20 kJ/$$mol and $$\Delta S = +0.05 kJ/($$mol\cdot K)$$. At T = 300$ K, what is $$\Delta G$ and is the reaction spontaneous?

Accepted Answer

$$\Delta G = -20 - (300 	imes 0.05) = -20 - 15 = -35 kJ/$$mol; the reaction is spontaneous.

Question 5

Which of the following statements about the laws of thermodynamics in biological systems is correct?

Accepted Answer

Cells transform energy from food molecules into ATP, heat, and mechanical work, but do not create or destroy energy.

Question 6

Which of the following best explains why living organisms do not violate the second law of thermodynamics?

Accepted Answer

They maintain internal order by continuously transforming energy and exporting disorder (entropy) to their surroundings.

Question 7

Which of the following reactions is most likely to be coupled to ATP hydrolysis in a cell?

Accepted Answer

An endergonic reaction with $$\Delta G \u003e 0$$, such as the synthesis of glutamine from glutamic acid and ammonia.

Question 8

What is the primary function of ATP in cellular metabolism?

Accepted Answer

To act as an energy carrier that couples exergonic and endergonic reactions.

Question 9

Which of the following best describes energy coupling in biological systems?

Accepted Answer

An energetically favorable (exergonic) reaction is linked to an energetically unfavorable (endergonic) reaction, allowing the overall process to proceed.

Question 10

A scientist is studying a reaction with $$\Delta G = +12 kJ/$$mol under standard conditions. Which of the following strategies could make this reaction proceed spontaneously in a cell?

Accepted Answer

Couple the reaction to ATP hydrolysis, which has a large negative $$\Delta G.$$

Question 11

Which of the following is an example of an anabolic pathway?

Accepted Answer

The synthesis of proteins from amino acids.

Question 12

If a reaction in a cell has $$\Delta G \u003c 0$$, which of the following is true?

Accepted Answer

The reaction is exergonic and can occur spontaneously.

Question 13

Which of the following statements about ATP hydrolysis is correct?

Accepted Answer

ATP hydrolysis is an exergonic reaction that releases free energy, which can be used to drive endergonic processes.

Question 14

In the synthesis of glutamine from glutamic acid and ammonia, what is the role of ATP?

Accepted Answer

ATP phosphorylates glutamic acid, creating a high-energy intermediate that allows the endergonic reaction to proceed.

Question 15

Which of the following best explains why exergonic reactions can drive endergonic reactions in cells?

Accepted Answer

The free energy released from exergonic reactions is used to power endergonic reactions through energy coupling.

Question 16

A cell needs to synthesize a molecule in a reaction with $$\Delta G = +8 kJ/$$mol. Which of the following is the most likely way the cell will accomplish this?

Accepted Answer

Couple the reaction to the hydrolysis of ATP, which has $$\Delta G = -30 kJ/$$mol, making the overall $$\Delta G$$ negative.

Question 17

Which of the following is NOT a correct statement about enzymes in metabolic pathways?

Accepted Answer

Enzymes are consumed during the reactions they catalyze.

Question 18

Which of the following best describes the relationship between catabolism and anabolism?

Accepted Answer

Catabolic reactions release energy that can be used to drive anabolic reactions.

Question 19

A cell is maintaining its highly ordered structure. According to the second law of thermodynamics, what must be true about the cell's energy transformations?

Accepted Answer

The cell must release heat and waste to its environment, increasing the entropy of the surroundings.

Cellular Metabolism and Energy Flow in Biological Systems

Guida di studio - Domande di pratica

Study guide - Flashcard