Question 1

Which of the following best describes a catabolic pathway in cellular metabolism?

Accepted Answer

A pathway that releases energy by breaking down complex molecules into simpler compounds.

Question 2

Which of the following is an example of kinetic energy in a biological system?

Accepted Answer

The movement of cilia on the surface of a paramecium.

Question 3

According to the first law of thermodynamics, which of the following statements is true?

Accepted Answer

Energy can be transferred and transformed, but cannot be created or destroyed.

Question 4

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

Accepted Answer

$$\Delta G = -40 kJ/$$mol

Question 5

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

Accepted Answer

They increase the entropy of their surroundings by releasing heat and waste products.

Question 6

Which of the following statements about ATP is correct?

Accepted Answer

ATP hydrolysis releases energy that can be used to drive endergonic reactions.

Question 7

A cell couples the conversion of glutamic acid to glutamine ($$\Delta G = +3.4$$ kcal/mol) with ATP hydrolysis ($$\Delta G = -7.3$$ kcal/mol). What is the overall $$\Delta G$$ for the coupled reaction?

Accepted Answer

$$\Delta G = -3.9$$ kcal/mol

Question 8

Which of the following is NOT a way that enzymes lower the activation energy ($$E_a) of a $$reaction?

Accepted Answer

Changing the overall $$\Delta G of $$the reaction.

Question 9

A competitive inhibitor differs from a noncompetitive inhibitor in that a competitive inhibitor:

Accepted Answer

Binds reversibly to the active site, blocking substrate binding.

Question 10

Which of the following best describes feedback inhibition in a metabolic pathway?

Accepted Answer

The end product of a pathway inhibits an enzyme that acts early in the pathway.

Question 11

Which of the following environmental changes is most likely to denature a human enzyme?

Accepted Answer

Lowering the pH from 7 to 2.

Question 12

Which of the following is an example of an allosteric regulation mechanism?

Accepted Answer

A regulatory molecule binding to a site other than the active site, stabilizing the enzyme's active form.

Question 13

Why do cells rarely reach metabolic equilibrium?

Accepted Answer

Because equilibrium would prevent the cell from doing work and lead to cell death.

Question 14

Which of the following best explains why vitamins are essential in the human diet?

Accepted Answer

They are used as coenzymes, which are required for enzyme function.

Question 15

A patient is exposed to a nerve gas that irreversibly inhibits acetylcholinesterase. What is the most likely effect on the patient's nervous system?

Accepted Answer

Accumulation of acetylcholine, causing continuous nerve stimulation and muscle contraction.

Question 16

Which of the following statements about the ATP cycle is correct?

Accepted Answer

ATP is regenerated from ADP by the addition of a phosphate group using energy from catabolic reactions.

Question 17

Which of the following scenarios best illustrates the concept of energy coupling in cells?

Accepted Answer

The exergonic hydrolysis of ATP is used to drive the endergonic synthesis of proteins.

Question 18

Which of the following is a correct statement about the relationship between free energy ($$G$$), stability, and equilibrium?

Accepted Answer

A system at equilibrium has maximum stability and minimum free energy.

Question 19

Which of the following best describes the role of enzymes in biological reactions?

Accepted Answer

Enzymes lower the activation energy, allowing reactions to occur more rapidly.

Chapter 8: An Introduction to Metabolism – Study Notes

Guida di studio - Domande di pratica

Study guide - Flashcard