Question 1

Which of the following best describes the difference between kinetic and potential energy, and provides a correct example of each?

Accepted Answer

Kinetic energy is the energy of motion, such as an antelope running; potential energy is stored energy, such as water held behind a dam.

Question 2

According to the second law of thermodynamics, what always happens during every energy transfer in biological systems?

Accepted Answer

Some energy is lost as heat, increasing the entropy of the universe.

Question 3

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

Accepted Answer

A reaction with $$\Delta G \u003c 0 is $$spontaneous and releases energy.

Question 4

Cellular respiration and photosynthesis are two major biological processes. Which statement correctly compares their energy changes?

Accepted Answer

Cellular respiration is exergonic ($$\Delta G \u003c 0$$); photosynthesis is endergonic and requires energy input from sunlight.

Question 5

A student mixes two chemicals in a beaker. The reaction does not proceed until the mixture is heated. Which concept best explains why heat is needed?

Accepted Answer

The reactants must reach the activation energy ($$E_A) to $$form the transition state.

Question 6

Which of the following is an example of a spontaneous process in a cell?

Accepted Answer

The breakdown of glucose during cellular respiration, releasing energy.

Question 7

Which equation correctly represents the change in free energy for a chemical reaction?

Accepted Answer

$$\Delta G = G_{products} - G_{reactants}$$

Question 8

Why does a spontaneous reaction not necessarily occur rapidly in a biological system?

Accepted Answer

Because the reaction may have a high activation energy barrier that slows its rate.

Question 9

Which of the following best describes the role of a catalyst in a chemical reaction?

Accepted Answer

It lowers the activation energy ($$E_A) $$required for the reaction to proceed.

Question 10

A cell must move ions against their concentration gradient. Which type of energy is primarily required for this process?

Accepted Answer

Potential energy stored in ATP molecules.

Question 11

Which of the following scenarios best illustrates the first law of thermodynamics in a biological context?

Accepted Answer

A plant converting sunlight into chemical energy during photosynthesis.

Question 12

If a reaction has $$\Delta G = 0$$, what does this indicate about the reaction?

Accepted Answer

The reaction is at equilibrium and no net work can be done.

Question 13

Which of the following is NOT a consequence of the second law of thermodynamics for living organisms?

Accepted Answer

All energy in cells is used efficiently with no loss.

Question 14

A reaction in a cell has $$\Delta G = +15 kJ/$$mol. Which of the following statements is true?

Accepted Answer

The reaction is endergonic and requires energy input.

Question 15

Which of the following best explains why the energy stored in an apple is considered potential energy?

Accepted Answer

It is stored in the chemical bonds of molecules within the apple.

Question 16

Which of the following is true about the relationship between reactants and products in an exergonic reaction?

Accepted Answer

The reactants have higher free energy than the products.

Question 17

A scientist observes that a reaction in a test tube does not proceed until an enzyme is added. What is the most likely explanation?

Accepted Answer

The enzyme lowers the activation energy barrier, allowing the reaction to proceed.

Question 18

Which of the following best describes equilibrium in a metabolic reaction?

Accepted Answer

The rates of the forward and reverse reactions are equal, and there is no net change in free energy.

Question 19

Which of the following is an example of work performed by cells that requires energy?

Accepted Answer

Active transport of sodium ions out of the cell against their concentration gradient.

Question 20

Which of the following statements about the transition state of a chemical reaction is correct?

Accepted Answer

It is the state where reactants have absorbed enough energy to break bonds and form products.

An Introduction to Energy and Metabolism in Biological Systems

Study Guide - Practice Questions