Question 1

Which of the following best describes the purpose of a pulse-chase experiment in cell biology?

Accepted Answer

To track the movement of newly synthesized proteins through cellular compartments using radioactively labeled amino acids.

Question 2

During a pulse-chase experiment, why are cells first exposed to radioactively labeled amino acids and then to non-radioactive amino acids?

Accepted Answer

To allow only proteins synthesized during the pulse to be labeled, so their movement can be tracked during the chase.

Question 3

Which organelle is primarily responsible for the breakdown of macromolecules and is only present in animal cells?

Accepted Answer

Lysosome

Question 4

A cell is observed to engulf a bacterium, enclosing it in a membrane-bound vesicle. Which process is this an example of?

Accepted Answer

Phagocytosis

Question 5

Which of the following is NOT a function of the smooth endoplasmic reticulum (SER)?

Accepted Answer

Protein synthesis for secretion

Question 6

Which evidence supports the endosymbiotic theory for the origin of mitochondria and chloroplasts?

Accepted Answer

They contain their own circular DNA and replicate by binary fission.

Question 7

Which cytoskeletal filament is primarily responsible for muscle contraction in animal cells?

Accepted Answer

Actin filaments (microfilaments)

Question 8

A scientist observes a cell crawling along a surface by extending its leading edge. Which cytoskeletal component and associated motor protein are most directly involved in this movement?

Accepted Answer

Actin filaments and myosin

Question 9

Which of the following statements about microtubules is TRUE?

Accepted Answer

They are hollow tubes made of $$\alpha- $$and $$\beta-$$tubulin dimers and are involved in organelle transport.

Question 10

Which motor protein moves towards the plus end of microtubules, transporting vesicles and organelles within the cell?

Accepted Answer

Kinesin

Question 11

A mutation prevents the polymerization of actin filaments in a cell. Which process would be most directly affected?

Accepted Answer

Cytokinesis in animal cells

Question 12

Which of the following best explains why eukaryotic cells are generally larger than prokaryotic cells?

Accepted Answer

Eukaryotic cells contain internal membrane-bound organelles that compartmentalize functions, allowing for increased size.

Question 13

Which of the following is a key difference between bacterial and eukaryotic flagella?

Accepted Answer

Eukaryotic flagella have a 9+2 arrangement of microtubules and are powered by dynein, while bacterial flagella are powered by a rotary motor.

Question 14

Which cytoskeletal element is most important for maintaining the mechanical strength of epithelial cells, such as those in skin and hair?

Accepted Answer

Intermediate filaments (keratin)

Question 15

A vesicle is transported from the center of a cell towards the plasma membrane. Which cytoskeletal element and motor protein are primarily responsible for this movement?

Accepted Answer

Microtubules and kinesin

Question 16

Which process is most directly responsible for the uptake of cholesterol from the bloodstream into animal cells?

Accepted Answer

Endocytosis

Question 17

Which of the following best describes the dynamic instability of microtubules?

Accepted Answer

Microtubules can rapidly grow by polymerization and shrink by depolymerization at their plus ends.

Question 18

Which of the following is a function of the central vacuole in plant cells?

Accepted Answer

Storage and digestion

Question 19

Which of the following best explains the role of dynein in eukaryotic cells?

Accepted Answer

It moves towards the minus end of microtubules, powering cilia and flagella movement.

Question 20

A patient has a genetic defect that prevents the formation of lysosomes. Which cellular process would be most directly impaired?

Accepted Answer

Digestion of macromolecules and recycling of cellular components

Eukaryotic Cell Structure and Function: Organelles, Cytoskeleton, and Cellular Processes

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