Question 1

Which of the following best describes the difference between catabolic and anabolic pathways in metabolism?

Accepted Answer

Catabolic pathways break down complex molecules into simpler ones, releasing energy, while anabolic pathways build complex molecules from simpler ones, requiring energy.

Question 2

In a chemical reaction, you start with reactants that in total have 7 carbon atoms. How many carbons will be present in the products, according to the law of conservation of matter?

Accepted Answer

7

Question 3

Which of the following is a likely product of a catabolic pathway?

Accepted Answer

An amino acid like isoleucine

Question 4

Which of the following statements about free energy ($$G) is $$correct?

Accepted Answer

Free energy is the amount of energy in a system that is available to do work at constant temperature and pressure.

Question 5

Given the equation $$\Delta G = G_{	ext{products}} - G_{	ext{reactants}}$$, what does a negative $$\Delta G$$ indicate about a reaction?

Accepted Answer

The reaction is exergonic and releases energy.

Question 6

Which of the following best explains why ATP hydrolysis is often coupled to endergonic reactions in cells?

Accepted Answer

ATP hydrolysis is exergonic ($$\Delta G  0) $$when coupled.

Question 7

Which of the following is true regarding the activation energy ($$E_A) of a $$reaction?

Accepted Answer

Activation energy is the energy required to initiate a reaction, but does not affect $$\Delta G.$$

Question 8

What is the primary role of enzymes in biological reactions?

Accepted Answer

Enzymes lower the activation energy ($$E_A$$), increasing the rate of reaction.

Question 9

Which of the following scenarios describes an exergonic reaction?

Accepted Answer

Melting ice at room temperature

Question 10

A reaction has a $$\Delta G of$$ $$+3.4$$ kcal/mol. If it is coupled with ATP hydrolysis ($$\Delta G = -7.3$$ kcal/mol), what is the overall $$\Delta G$$ for the coupled reaction?

Accepted Answer

$$-3.9$$ kcal/mol

Question 11

Which of the following is NOT a way that an enzyme's active site can lower activation energy?

Accepted Answer

Increasing the $$\Delta G of $$the reaction

Question 12

What happens to most enzymes if the temperature is raised significantly above their optimal range (e.g., from 37°C to 70°C)?

Accepted Answer

They denature, losing their functional three-dimensional structure.

Question 13

Which of the following statements about enzymes is correct?

Accepted Answer

Enzymes lower the activation energy but do not change the $$\Delta G of a $$reaction.

Question 14

A particular enzyme is found both in E. coli (a human gut bacterium) and a bacterium living in the Great Salt Lake. Which enzyme is likely to function best in high salt conditions?

Accepted Answer

The enzyme from the Great Salt Lake bacterium

Question 15

Which of the following best describes the fate of energy released in an exergonic reaction in a cell?

Accepted Answer

It is used to power other reactions or lost as heat.

Question 16

Which of the following reactions has a higher activation energy?

Accepted Answer

Conversion of diamond into graphite

Question 17

Which of the following is NOT a characteristic of a spontaneous reaction?

Accepted Answer

It always happens quickly.

Question 18

Which of the following best explains why enzymes are highly specific for their substrates?

Accepted Answer

The active site of an enzyme has a unique shape and chemical environment that matches only specific substrates.

Question 19

Which of the following statements about the relationship between activation energy and reaction rate is correct?

Accepted Answer

A lower activation energy means the reaction will proceed more quickly.

Metabolism, Energy, and Enzymes: Foundations of Cellular Biochemistry

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