Question 1

A red blood cell is placed in a solution with a lower solute concentration than its cytoplasm. Which of the following best describes what will happen to the cell, and why?

Accepted Answer

Water will move into the cell by osmosis, causing it to swell, because the solution is hypotonic relative to the cytoplasm.

Question 2

Which of the following statements correctly distinguishes between simple diffusion and facilitated diffusion across a biological membrane?

Accepted Answer

Simple diffusion does not require membrane proteins, while facilitated diffusion requires specific transport proteins.

Question 3

The sodium-potassium pump (Na⁺/K⁺-ATPase) is an example of which type of membrane transport, and what is its main function?

Accepted Answer

Primary active transport; it uses ATP hydrolysis to move 3 Na⁺ out and 2 K⁺ into the cell against their concentration gradients.

Question 4

Which of the following best describes the role of the GLUT1 transporter in human cells?

Accepted Answer

It facilitates the passive transport of glucose into cells via a carrier protein, following the concentration gradient.

Question 5

During glycolysis, which step is responsible for the substrate-level phosphorylation of ADP to ATP, and what is the net ATP gain per glucose molecule?

Accepted Answer

Phosphoenolpyruvate to pyruvate catalyzed by pyruvate kinase; net gain is 2 ATP per glucose.

Question 6

Which of the following best explains why ATP is considered an important energy intermediate in cellular metabolism?

Accepted Answer

ATP hydrolysis releases free energy that can be coupled to endergonic reactions, due to the high-energy phosphate bonds.

Question 7

A patient with a genetic defect in the pyruvate dehydrogenase complex is likely to experience which of the following metabolic consequences?

Accepted Answer

Accumulation of pyruvate and lactic acid due to impaired conversion of pyruvate to acetyl-CoA.

Question 8

Which of the following statements about the electron transport system (ETS) in mitochondria is correct?

Accepted Answer

Electrons flow from NADH and FADH₂ through a series of carriers with increasing standard reduction potential, ultimately reducing O₂ to H₂O.

Question 9

Which of the following best describes the function of ATP synthase in mitochondria?

Accepted Answer

It uses the proton gradient across the inner mitochondrial membrane to drive the synthesis of ATP from ADP and inorganic phosphate ($$ \mathrm{ADP} + \mathrm{P_i} \rightarrow \mathrm{ATP} ).$$

Question 10

Which of the following is a key difference between substrate-level phosphorylation and oxidative phosphorylation?

Accepted Answer

Substrate-level phosphorylation directly transfers a phosphate group to ADP from a phosphorylated intermediate, while oxidative phosphorylation uses a proton gradient generated by the electron transport chain.

Question 11

Which of the following best describes the role of Rubisco in photosynthesis?

Accepted Answer

It catalyzes the fixation of CO₂ to ribulose-1,5-bisphosphate in the Calvin Cycle.

Question 12

A plant exposed to high temperatures and low CO₂ concentrations is likely to experience increased rates of photorespiration. Which adaptation helps minimize photorespiration in such conditions?

Accepted Answer

C₄ photosynthesis, which spatially separates CO₂ fixation from the Calvin Cycle.

Question 13

Which of the following statements about the endomembrane system is correct?

Accepted Answer

The rough endoplasmic reticulum is involved in the synthesis of membrane-bound and secretory proteins, while the smooth ER is involved in lipid synthesis and detoxification.

Question 14

Which of the following best describes the process of receptor-mediated endocytosis?

Accepted Answer

Specific ligands bind to cell surface receptors, triggering the formation of clathrin-coated vesicles that internalize the ligand-receptor complexes.

Question 15

A mutation that disrupts the function of SNARE proteins would most directly affect which cellular process?

Accepted Answer

Vesicle targeting and fusion with the correct membrane compartment.

Question 16

Which of the following best explains the function of the malate-aspartate shuttle in eukaryotic cells?

Accepted Answer

It transfers electrons from cytosolic NADH into the mitochondria for use in the electron transport chain.

Question 17

During strenuous exercise, muscle cells rely on the Cori Cycle. What is the main function of the Cori Cycle?

Accepted Answer

It transports lactate produced in muscles to the liver, where it is converted back to glucose.

Question 18

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

Accepted Answer

Three turns of the Calvin Cycle are required to produce one molecule of glyceraldehyde-3-phosphate (G3P).

Question 19

Which of the following best describes the role of clathrin in vesicular transport?

Accepted Answer

Clathrin forms a coat around vesicles budding from the trans-Golgi network and plasma membrane, aiding in vesicle formation.

Cell Biology Study Guide: Membrane Transport, Metabolism, Photosynthesis, and the Endomembrane System

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