Question 1

Which of the following best describes the main structural difference between rough and smooth endoplasmic reticulum (ER)?

Accepted Answer

Rough ER has ribosomes attached to its cytosolic surface, while smooth ER lacks ribosomes.

Question 2

A liver cell is exposed to a new drug. Which organelle is primarily responsible for detoxifying this drug, and what modification does it perform?

Accepted Answer

Smooth ER; adds hydroxyl (OH) groups to increase hydrophilicity.

Question 3

During protein glycosylation, which molecule acts as the initial carrier for the core oligosaccharide before it is transferred to the protein?

Accepted Answer

Dolichol phosphate

Question 4

Which of the following best explains the role of flippases in the ER membrane?

Accepted Answer

They translocate specific phospholipids from one leaflet of the ER membrane to the other, maintaining membrane asymmetry.

Question 5

Which of the following sequences correctly describes the maturation of a phagocytosed particle in a cell?

Accepted Answer

Phagocytic vacuole → early endosome → late endosome → lysosome

Question 6

Which process is most directly responsible for the breakdown of glycogen in the liver to regulate blood glucose levels?

Accepted Answer

Smooth ER carbohydrate metabolism

Question 7

A mutation prevents the hydrolysis of GTP in the Ran protein. What is the most likely consequence for nuclear import?

Accepted Answer

Importin cannot be recycled, leading to impaired nuclear import of proteins.

Question 8

Which of the following best describes the difference between exocytosis and endocytosis?

Accepted Answer

Exocytosis moves materials out of the cell, while endocytosis brings materials into the cell.

Question 9

Which organelle is continuous with the outer membrane of the nuclear envelope?

Accepted Answer

Endoplasmic reticulum (ER)

Question 10

Which of the following steps occurs first in the Ran/importin pathway for nuclear import?

Accepted Answer

Importin binds to a protein with a nuclear localization signal (NLS) in the cytoplasm.

Question 11

Which of the following is a function of the Golgi apparatus in the secretory pathway?

Accepted Answer

Modifies and sorts proteins received from the ER for transport to their final destinations.

Question 12

A protein destined for secretion is synthesized by ribosomes on the rough ER. What is the next step in its journey?

Accepted Answer

It is inserted into the ER lumen for folding and initial glycosylation.

Question 13

Which of the following best describes the stationary cisternae model of Golgi operation?

Accepted Answer

Each cisterna is stable, and shuttle vesicles move cargo between them.

Question 14

Which of the following is TRUE regarding nuclear pore complexes (NPCs)?

Accepted Answer

Small molecules and ions can freely diffuse through NPCs, but larger molecules require active transport.

Question 15

Which of the following is a direct result of ER-associated degradation (ERAD)?

Accepted Answer

Misfolded proteins are sent to the cytosol for degradation by proteasomes.

Question 16

Which of the following is a function of the smooth ER in steroid-producing cells?

Accepted Answer

Biosynthesis of cholesterol and steroid hormones such as testosterone and estradiol.

Question 17

A cell is unable to lower the pH in its late endosomes. Which process will be most directly affected?

Accepted Answer

Conversion of late endosomes into functional lysosomes.

Question 18

Which of the following best explains why some phospholipids are retained in a specific monolayer of the ER membrane?

Accepted Answer

There is no flippase available to translocate those specific lipids to the other leaflet.

Question 19

Which of the following is TRUE about the relationship between the nuclear envelope and the ER?

Accepted Answer

The outer membrane of the nuclear envelope is continuous with the ER membrane.

Endomembrane System, ER, Golgi, Glycosylation, and Nuclear Transport: Study Notes for Cell Biology

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