Question 1

Which of the following best describes the main function of the plasma membrane in a eukaryotic cell?

Accepted Answer

It provides a selectively permeable boundary that regulates the movement of substances into and out of the cell.

Question 2

A patient is given an intravenous solution that is hypertonic relative to their red blood cells. What is the most likely effect on the red blood cells, and why?

Accepted Answer

The cells will shrink (crenate) because water will move out of the cells into the hypertonic solution.

Question 3

Which of the following transport mechanisms requires energy in the form of ATP and moves substances against their concentration gradient?

Accepted Answer

Primary active transport

Question 4

A cell is placed in a solution and begins to swell. Which of the following best describes the tonicity of the solution relative to the cell, and the direction of water movement?

Accepted Answer

The solution is hypotonic; water moves into the cell.

Question 5

Which of the following best explains why oxygen ($$O_2) $$can diffuse directly through the plasma membrane, while glucose cannot?

Accepted Answer

Oxygen is small and nonpolar, allowing it to pass through the hydrophobic core of the membrane, while glucose is large and polar, requiring a transport protein.

Question 6

A mutation causes a cell to lack functional desmosomes. Which tissue would be most affected by this defect, and what would be the likely consequence?

Accepted Answer

Epithelial tissue; increased susceptibility to mechanical stress and tearing.

Question 7

Which of the following best describes the role of the sodium-potassium pump ($$Na^+/K^+$$ ATPase) in maintaining cellular homeostasis?

Accepted Answer

It pumps $$3$$ sodium ions out of the cell and $$2$$ potassium ions into the cell against their concentration gradients, using ATP.

Question 8

A white blood cell engulfs a bacterium by surrounding it with its plasma membrane, forming a vesicle that is then digested. Which process is being described?

Accepted Answer

Phagocytosis

Question 9

Which of the following statements about the structure of the plasma membrane is correct?

Accepted Answer

The hydrophilic heads of phospholipids face the extracellular and intracellular fluids, while the hydrophobic tails face each other in the interior of the bilayer.

Question 10

A cell in the small intestine absorbs nutrients by taking in small droplets of extracellular fluid. Which process is responsible for this?

Accepted Answer

Pinocytosis

Question 11

During which phase of the cell cycle does DNA replication occur?

Accepted Answer

S phase

Question 12

Which of the following best describes the function of the nucleolus?

Accepted Answer

It is the site of ribosomal RNA synthesis and assembly of ribosomal subunits.

Question 13

A cell is observed to have abundant smooth endoplasmic reticulum. Which of the following is the most likely function of this cell?

Accepted Answer

Lipid metabolism and detoxification of drugs

Question 14

Which cytoskeletal element is primarily responsible for resisting mechanical stress and is often attached to desmosomes?

Accepted Answer

Intermediate filaments

Question 15

A neuron releases neurotransmitters into the synaptic cleft by fusing vesicles with the plasma membrane. Which process is this an example of?

Accepted Answer

Exocytosis

Question 16

Which of the following best explains why mitochondria are especially abundant in muscle cells?

Accepted Answer

Muscle cells require large amounts of ATP for contraction, which is produced by mitochondria.

Question 17

Which of the following best describes the function of the Golgi apparatus?

Accepted Answer

It modifies, sorts, and packages proteins and lipids for secretion or delivery to other organelles.

Question 18

A cell is exposed to a toxin that inhibits the function of peroxisomes. Which of the following processes would be most directly affected?

Accepted Answer

Detoxification of harmful substances such as alcohol and neutralization of free radicals

Question 19

Which of the following best describes the role of microvilli on the surface of intestinal epithelial cells?

Accepted Answer

They increase the surface area for absorption of nutrients.

Question 20

During mitosis, at which phase do the chromosomes align along the spindle equator, and what is the significance of this alignment?

Accepted Answer

Metaphase; it ensures that each daughter cell will receive an identical set of chromosomes.

Cell Structure and Function: Study Notes for Anatomy & Physiology

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