Question 1

Which of the following best describes the first law of thermodynamics as it applies to cellular energetics?

Accepted Answer

Energy is transferred and transformed, but the total amount remains constant.

Question 2

A scientist observes that an enzyme-catalyzed reaction proceeds much faster than the same reaction without the enzyme. What is the primary reason for this increased rate?

Accepted Answer

The enzyme lowers the activation energy required for the reaction.

Question 3

Which of the following environmental changes is most likely to denature an enzyme and decrease its activity?

Accepted Answer

A drastic change in pH away from the enzyme's optimum.

Question 4

During cellular respiration, which process directly produces the most ATP?

Accepted Answer

Electron transport chain and oxidative phosphorylation

Question 5

Which of the following equations correctly represents the overall process of aerobic cellular respiration?

Accepted Answer

$$\mathrm{C}_6\mathrm{H}_{12}\mathrm{O}_6 + 6\ \mathrm{O}_2 ightarrow 6\ \mathrm{CO}_2 + 6\ \mathrm{H}_2\mathrm{O} + 	ext{energy}$$

Question 6

A competitive inhibitor affects an enzyme-catalyzed reaction by:

Accepted Answer

Binding to the active site and preventing substrate binding.

Question 7

Which of the following best explains why cyanide poisoning is fatal to humans?

Accepted Answer

Cyanide inhibits the electron transport chain, stopping ATP production.

Question 8

In photosynthesis, what is the main role of chlorophyll?

Accepted Answer

To absorb light energy and transfer it to electrons.

Question 9

Which of the following statements about fermentation is correct?

Accepted Answer

Fermentation occurs in the absence of oxygen and regenerates NAD$$^+$$ for glycolysis.

Question 10

A bear and a ground squirrel are both exposed to cold temperatures. The bear maintains a constant body temperature, while the squirrel's body temperature drops. Which metabolic strategy does the bear use?

Accepted Answer

Endothermy

Question 11

Which of the following best describes the relationship between the light-dependent reactions and the Calvin cycle in photosynthesis?

Accepted Answer

The light-dependent reactions provide ATP and NADPH to power the Calvin cycle.

Question 12

If the concentration of hydrogen ions increases in a cell's cytoplasm, what happens to the pH?

Accepted Answer

The pH decreases.

Question 13

Which of the following is an example of a negative feedback mechanism in cellular metabolism?

Accepted Answer

A product of a metabolic pathway inhibits an enzyme involved earlier in the pathway.

Question 14

Which of the following best explains why increasing temperature initially increases the rate of an enzyme-catalyzed reaction, but then decreases it at higher temperatures?

Accepted Answer

Enzymes denature at high temperatures, losing their functional shape.

Question 15

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

Accepted Answer

Glycolysis $$\rightarrow$$ Citric Acid Cycle $$\rightarrow$$ Electron Transport Chain

Question 16

Which of the following best describes the function of ATP synthase in cellular respiration?

Accepted Answer

It synthesizes ATP as protons flow down their gradient through the enzyme.

Question 17

A mutation causes an enzyme's active site to change shape. What is the most likely effect on the enzyme's function?

Accepted Answer

The enzyme will not bind its substrate as effectively, reducing its activity.

Question 18

Which of the following is a direct product of the light-dependent reactions of photosynthesis?

Accepted Answer

ATP

Question 19

Which of the following best explains why allosteric regulation is important for enzyme function?

Accepted Answer

It enables enzymes to be regulated by molecules binding at sites other than the active site.

Question 20

Which of the following best explains why mitochondria are often called the 'powerhouse' of the cell?

Accepted Answer

They generate most of the cell's ATP through aerobic respiration.

Unit 4: Cellular Energetics – Study Notes for General Biology

Study Guide - Practice Questions

Study Guide - Flashcards