Question 1

Which of the following statements best describes the Second Law of Thermodynamics as it applies to biological systems?

Accepted Answer

Every energy transfer increases the entropy (disorder) of the universe.

Question 2

A scientist is studying an enzyme-catalyzed reaction. She increases the temperature slightly and observes an increase in reaction rate. However, when she increases the temperature further, the reaction rate drops sharply. What is the most likely explanation for this observation?

Accepted Answer

The enzyme denatures at high temperatures, losing its functional shape.

Question 3

Which of the following equations correctly represents the calculation of Gibbs Free Energy ($$\Delta G) $$for a chemical reaction?

Accepted Answer

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

Question 4

During glycolysis, glucose is converted into two molecules of pyruvate. Which of the following best describes the net energy yield from glycolysis per molecule of glucose?

Accepted Answer

2 ATP and 2 NADH

Question 5

Which of the following best explains why fermentation is less efficient than aerobic cellular respiration in terms of ATP production?

Accepted Answer

Fermentation does not fully oxidize glucose, so less energy is extracted.

Question 6

A student is asked to distinguish between an exergonic and an endergonic reaction. Which of the following statements is correct?

Accepted Answer

Exergonic reactions release energy and have a negative $$\Delta G.$$

Question 7

Which of the following is a correct description of the role of oxygen in aerobic cellular respiration?

Accepted Answer

Oxygen is reduced to form water at the end of the electron transport chain.

Question 8

Which of the following best describes the function of coenzymes such as NAD$$^+$$ and FAD in cellular respiration?

Accepted Answer

They serve as electron carriers, accepting and donating electrons during redox reactions.

Question 9

A researcher adds a competitive inhibitor to an enzyme-catalyzed reaction. Which of the following best describes the effect of the inhibitor?

Accepted Answer

The inhibitor binds to the enzyme's active site, preventing substrate binding.

Question 10

Which of the following statements about the Calvin Cycle is correct?

Accepted Answer

It fixes carbon dioxide into organic molecules using ATP and NADPH.

Question 11

Which of the following best describes the relationship between photosynthesis and cellular respiration?

Accepted Answer

Photosynthesis produces glucose and oxygen, which are used in cellular respiration to produce ATP, carbon dioxide, and water.

Question 12

A student is examining a leaf under a microscope and observes green structures. Which organelle is responsible for the green color, and what pigment does it contain?

Accepted Answer

Chloroplasts; chlorophyll

Question 13

Which of the following best describes the chemiosmotic hypothesis for ATP synthesis in mitochondria?

Accepted Answer

A proton gradient across the inner mitochondrial membrane drives ATP synthesis via ATP synthase.

Question 14

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

Accepted Answer

Photosynthesis

Question 15

A scientist is measuring the rate of an enzyme-catalyzed reaction at different substrate concentrations. She observes that the reaction rate increases with substrate concentration but eventually levels off. What is the most likely explanation for this observation?

Accepted Answer

All enzyme active sites are saturated with substrate, so the reaction rate reaches a maximum.

Question 16

Which of the following best describes the main difference between autotrophs and heterotrophs?

Accepted Answer

Autotrophs use light or inorganic chemicals to produce organic molecules, while heterotrophs consume organic molecules.

Question 17

Which of the following is the correct order of steps in the scientific method?

Accepted Answer

Observation, Hypothesis, Experiment, Data Collection, Conclusion

Question 18

A student is conducting a fermentation experiment with yeast and measures the amount of CO$$_2$$ produced. Which variable is the dependent variable in this experiment?

Accepted Answer

The amount of CO$$_2$$ produced

Question 19

Which of the following is a correct statement about the storage form of glucose in animals?

Accepted Answer

Glucose is stored as glycogen in animal cells.

Question 20

Which of the following best describes the role of phosphorylation in regulating enzyme activity?

Accepted Answer

Phosphorylation can either activate or deactivate enzymes, depending on the enzyme.

Exam 3 Study Guide: Energy, Metabolism, Cellular Respiration, and Photosynthesis

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