Question 1

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

Accepted Answer

Energy cannot be created or destroyed, only transformed from one form to another.

Question 2

A chemical reaction has a $$\Delta G ($$change in free energy) of $$-15 kJ/$$mol. Which of the following is true about this reaction?

Accepted Answer

It is exergonic and will occur spontaneously.

Question 3

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 three-dimensional shape that fits only specific substrates.

Question 4

During glycolysis, one molecule of glucose is broken down into two molecules of pyruvate. What is the net gain of ATP molecules per glucose during glycolysis?

Accepted Answer

2 ATP

Question 5

Which of the following best describes the role of NAD+ in cellular respiration?

Accepted Answer

It acts as an electron carrier, accepting electrons during glycolysis and the Krebs cycle.

Question 6

A competitive inhibitor affects an enzyme-catalyzed reaction by:

Accepted Answer

Binding to the active site, preventing the substrate from binding.

Question 7

Which of the following is a correct statement about the Second Law of Thermodynamics in biological systems?

Accepted Answer

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

Question 8

Which of the following best describes the difference between C3 and C4 photosynthesis?

Accepted Answer

C3 plants use the Calvin cycle directly, while C4 plants initially fix carbon into a four-carbon compound before entering the Calvin cycle.

Question 9

If an enzyme is denatured by high temperature, what is the most likely effect on its function?

Accepted Answer

The enzyme will lose its specific shape and become nonfunctional.

Question 10

Which of the following is true about the relationship between activation energy and enzymes?

Accepted Answer

Enzymes lower the activation energy, making reactions proceed faster.

Question 11

Which of the following best describes substrate-level phosphorylation?

Accepted Answer

ATP is produced directly by transferring a phosphate group from a substrate to ADP.

Question 12

A noncompetitive inhibitor affects an enzyme-catalyzed reaction by:

Accepted Answer

Binding to an allosteric site, changing the enzyme's shape and reducing its activity.

Question 13

Which of the following is a product of the Krebs Cycle (Citric Acid Cycle)?

Accepted Answer

NADH

Question 14

Which of the following best explains why the shape of an enzyme's active site is important?

Accepted Answer

It determines the enzyme's specificity for its substrate.

Question 15

Which of the following is true about the effect of pH on enzyme activity?

Accepted Answer

Each enzyme has an optimal pH, and deviations can disrupt its structure and function.

Question 16

Which of the following is a correct statement about the Calvin Cycle?

Accepted Answer

It requires multiple turns to produce one molecule of glucose.

Question 17

Which of the following best describes the function of ATP in the cell?

Accepted Answer

It acts as the main energy currency, providing energy for cellular processes.

Question 18

Which of the following is true about the relationship between catabolism and anabolism?

Accepted Answer

Catabolism breaks down molecules to release energy, while anabolism uses energy to build complex molecules.

Question 19

Which of the following best explains why C4 and CAM plants are more efficient in hot, dry environments than C3 plants?

Accepted Answer

They minimize photorespiration by separating carbon fixation from the Calvin cycle in space (C4) or time (CAM).

Question 20

Which of the following best describes the effect of a noncompetitive inhibitor on the kinetic parameters of an enzyme-catalyzed reaction?

Accepted Answer

$$V_{max} is $$reduced, but $$K_m$$ remains unchanged.

General Biology Study Guide: Energy, Metabolism, Enzymes, Cellular Respiration, and Photosynthesis (Chapters 6-8)

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