Question 1

Which of the following best explains why living organisms require a constant input of energy?

Accepted Answer

To maintain highly ordered structures and drive endergonic reactions that would not occur spontaneously.

Question 2

A scientist observes that when the temperature of an enzyme-catalyzed reaction is increased from 20°C to 30°C, the reaction rate doubles. Which formula would best describe this temperature sensitivity?

Accepted Answer

The temperature coefficient $$Q_{10}$$, calculated as $$Q_{10} = \frac{R_2$}{R_1$}^{\frac{10}{T_2$-T_1$}}$$

Question 3

Which of the following statements about the second law of thermodynamics and living systems is correct?

Accepted Answer

Living systems increase local order but overall increase the entropy of the universe.

Question 4

During cellular respiration, what is the primary role of oxygen in the mitochondria?

Accepted Answer

It acts as the final electron acceptor in the electron transport chain, forming water.

Question 5

Which of the following best describes how ATP is synthesized during the light reactions of photosynthesis?

Accepted Answer

ATP synthase uses the proton gradient across the thylakoid membrane to convert ADP and inorganic phosphate into ATP.

Question 6

A mutation causes an enzyme's active site to change shape. Which is the most likely consequence?

Accepted Answer

The enzyme's substrate may no longer bind efficiently, reducing or eliminating catalytic activity.

Question 7

Which of the following is a key difference between competitive and non-competitive enzyme inhibitors?

Accepted Answer

Competitive inhibitors bind to the active site, while non-competitive inhibitors bind to a different site on the enzyme.

Question 8

Which of the following best explains why plants perform both photosynthesis and cellular respiration?

Accepted Answer

Photosynthesis captures and stores energy, while cellular respiration releases stored energy for cellular work.

Question 9

Which of the following is a correct sequence of events during aerobic cellular respiration?

Accepted Answer

Glycolysis → Pyruvate oxidation → Citric Acid Cycle → Electron Transport Chain

Question 10

A patient is diagnosed with a mitochondrial disorder that prevents the formation of a proton gradient across the inner mitochondrial membrane. Which process would be most directly affected?

Accepted Answer

ATP synthesis by ATP synthase

Question 11

Which of the following adaptations would you expect to find in plants living in hot, arid environments to maximize photosynthetic efficiency?

Accepted Answer

Evolution of C4 or CAM pathways to minimize photorespiration and water loss.

Question 12

Which of the following statements about redox reactions in cellular respiration is correct?

Accepted Answer

Glucose is oxidized to carbon dioxide, and oxygen is reduced to water.

Question 13

Which of the following best describes the fate of pyruvate under anaerobic conditions in human muscle cells?

Accepted Answer

It is converted to lactate through fermentation, regenerating NAD+.

Question 14

Which of the following is a similarity between the electron transport chains in mitochondria and chloroplasts?

Accepted Answer

Both use a proton gradient to drive ATP synthesis via ATP synthase.

Question 15

A researcher measures the metabolic rate per unit body mass in several animals and finds that smaller animals have higher rates than larger animals. Which of the following best explains this observation?

Accepted Answer

Smaller animals lose heat more rapidly due to a higher surface area-to-volume ratio, requiring higher metabolic rates.

Question 16

Which of the following best describes the role of NADH and FADH2 in cellular respiration?

Accepted Answer

They carry high-energy electrons to the electron transport chain for ATP production.

Question 17

Which of the following is a correct description of the Calvin cycle?

Accepted Answer

It uses ATP and NADPH from the light reactions to fix carbon dioxide into organic molecules.

Question 18

Which of the following best explains why increasing substrate concentration increases the rate of an enzyme-catalyzed reaction only up to a certain point?

Accepted Answer

All enzyme active sites become saturated with substrate, so the reaction rate levels off.

Question 19

Which of the following best describes the flow of energy through a food web?

Accepted Answer

Energy decreases at each successive trophic level due to loss as heat and metabolic processes.

Cellular Energetics: Energy, Enzymes, Respiration, and Photosynthesis

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