Question 1

Which statement best describes the First Law of Thermodynamics as it applies to biological systems?

Accepted Answer

Energy can neither be created nor destroyed, only transformed from one form to another.

Question 2

A cell converts glucose to ATP and heat. Which law of thermodynamics does the release of heat illustrate?

Accepted Answer

Second Law of Thermodynamics

Question 3

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

Accepted Answer

Photosynthesis in plant cells

Question 4

Which equation correctly relates the change in free energy ($$\Delta G) to $$enthalpy ($$\Delta H$$), entropy ($$\Delta S$$), and temperature ($$T$$)?

Accepted Answer

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

Question 5

A reaction has $$\Delta G = -20$$ kcal/mol. If you double the amount of enzyme present, what is the new $$\Delta G$$?

Accepted Answer

$$-20$$ kcal/mol

Question 6

Which of the following is NOT a way enzymes lower the activation energy of a reaction?

Accepted Answer

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

Question 7

Which type of metabolic pathway is most likely to involve oxidation reactions and release energy?

Accepted Answer

Catabolic pathway

Question 8

ATP is often described as the 'energy currency' of the cell. What property of ATP makes it suitable for this role?

Accepted Answer

Its triphosphate tail has repulsive negative charges, making hydrolysis highly exergonic.

Question 9

Which of the following best describes competitive inhibition of an enzyme?

Accepted Answer

The inhibitor binds to the active site, blocking substrate binding.

Question 10

Which statement about entropy is correct?

Accepted Answer

Entropy increases in a closed system over time.

Question 11

Which of the following is a real-life example of energy transfer by convection?

Accepted Answer

Heat loss from skin to air moving past the body

Question 12

Which of the following is true about metabolic equilibrium in living cells?

Accepted Answer

Cells are open systems and metabolism is never at equilibrium.

Question 13

Which of the following is an example of allosteric regulation?

Accepted Answer

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

Question 14

Which statement best explains why enzymes are sensitive to temperature and pH?

Accepted Answer

Temperature and pH can alter the R groups of amino acids, affecting enzyme shape and function.

Question 15

Which of the following is a function of cofactors in enzyme activity?

Accepted Answer

They help move electrons or hold substrates in place.

Question 16

A metabolic pathway is regulated by feedback inhibition. What is the likely effect of the end product on the pathway?

Accepted Answer

The end product inhibits an earlier step, preventing overproduction.

Question 17

Which of the following best describes the transition state in an enzyme-catalyzed reaction?

Accepted Answer

It is the unstable state where bonds are broken and new bonds are forming.

Question 18

Which of the following is true about the turnover number ($$k_{cat}) of an $$enzyme?

Accepted Answer

It is the number of substrate molecules converted to product per second by a single enzyme molecule.

Question 19

Which of the following is a correct statement about exergonic reactions?

Accepted Answer

They have a negative $$\Delta G$$ and occur spontaneously.

Question 20

Which of the following is an example of chemical energy in biological systems?

Accepted Answer

The energy stored in the bonds of glucose

Introduction to Metabolism and Thermodynamics in Biology

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