Question 1

Which of the following best describes the role of Rubisco in the Calvin cycle?

Accepted Answer

It fixes atmospheric CO$$_2 to a $$five-carbon molecule, initiating carbon fixation.

Question 2

During lactic acid fermentation, which molecule acts as the final electron acceptor?

Accepted Answer

Pyruvate

Question 3

Which of the following is a correct sequence for the secretory pathway of a protein destined for exocytosis?

Accepted Answer

Rough ER → Golgi apparatus → Vesicle → Exocytosis

Question 4

A cell is placed in a solution with a higher concentration of Na$$^+$$ outside than inside. Which transport mechanism is most likely used to move Na$$^+$$ into the cell against its concentration gradient?

Accepted Answer

Active transport using ATP

Question 5

Which statement about Gibbs free energy ($$	riangle G) is $$correct?

Accepted Answer

A negative $$	riangle G$$ means the reaction releases energy and is spontaneous.

Question 6

Which of the following best explains why enzymes increase the rate of chemical reactions?

Accepted Answer

They lower the activation energy barrier, allowing more reactant molecules to reach the transition state.

Question 7

A mutation causes a cell to lack gap junctions. Which process would be most directly affected?

Accepted Answer

Exchange of ions and small molecules between adjacent cells

Question 8

Which of the following is a direct result of the electron transport chain (ETC) in cellular respiration?

Accepted Answer

Pumping of protons across the inner mitochondrial membrane, creating a proton gradient

Question 9

Which process allows cells to continue producing ATP in the absence of oxygen?

Accepted Answer

Fermentation

Question 10

A patient is unable to produce sufficient NAD$$^+$$ during intense exercise. Which metabolic process would be most directly impaired?

Accepted Answer

Lactic acid fermentation

Question 11

Which of the following best describes the function of tight junctions in animal cells?

Accepted Answer

They prevent fluid leakage between cells.

Question 12

Which of the following is true about ATP as a cellular energy currency?

Accepted Answer

ATP stores energy in its high-energy phosphate bonds, which is released upon hydrolysis.

Question 13

Which of the following membrane transport mechanisms requires energy input from ATP?

Accepted Answer

Active transport

Question 14

Which statement best describes the difference between exergonic and endergonic reactions?

Accepted Answer

Exergonic reactions release energy; endergonic reactions require energy input.

Question 15

Which of the following is a function of carotenoids in plant leaves?

Accepted Answer

They absorb additional light wavelengths and protect against oxidative damage.

Question 16

A cell exposed to a toxin that blocks aquaporin channels would most likely show which effect?

Accepted Answer

Impaired water transport across the plasma membrane

Question 17

Which of the following is a correct description of paracrine signaling?

Accepted Answer

A cell releases signals that act on nearby cells.

Question 18

Which of the following best explains why unsaturated fatty acids help maintain membrane fluidity at low temperatures?

Accepted Answer

They introduce kinks in the fatty acid chains, preventing tight packing.

Question 19

Which of the following is a direct consequence of coupling energy-releasing and energy-requiring reactions in cells?

Accepted Answer

Cells can perform endergonic reactions by using the energy released from exergonic reactions.

Question 20

A scientist measures the rate of an enzyme-catalyzed reaction and finds that increasing substrate concentration no longer increases the reaction rate. What is the most likely explanation?

Accepted Answer

The enzyme has reached its maximum velocity ($$V_{max}) $$and is saturated with substrate.

General Biology: Cellular Processes, Signaling, and Energy Metabolism

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