Question 1

Which of the following best describes the function of the plasma membrane in a typical animal cell?

Accepted Answer

It surrounds the cell, regulates the movement of substances in and out, and facilitates communication with the environment.

Question 2

A red blood cell is placed in a hypertonic solution. What will happen to the cell, and why?

Accepted Answer

The cell will shrink (crenate) because water moves out of the cell to the area of higher solute concentration.

Question 3

Which of the following is a function of integral (transmembrane) proteins in the plasma membrane?

Accepted Answer

They serve as channels or carriers to facilitate the movement of specific substances across the membrane.

Question 4

Which organelle is responsible for the majority of ATP production in a eukaryotic cell, and what is the main process it uses?

Accepted Answer

Mitochondrion; oxidative metabolism

Question 5

A cell is actively transporting sodium ions ($\mathrm{Na^+}$) out and potassium ions ($\mathrm{K^+}$) in, both against their concentration gradients. Which transport mechanism is being used, and what is the energy source?

Accepted Answer

Primary active transport; energy from ATP hydrolysis

Question 6

Which of the following best explains why the phospholipid bilayer forms the basic structure of the plasma membrane?

Accepted Answer

Phospholipids are amphiphilic, with hydrophilic heads facing water and hydrophobic tails facing inward, creating a stable barrier.

Question 7

A patient receives an intravenous solution that is hypotonic relative to their blood plasma. What is the most likely effect on their red blood cells?

Accepted Answer

The cells will swell and may burst as water enters the cells.

Question 8

Which of the following is NOT a function of membrane proteins?

Accepted Answer

Synthesizing DNA for the nucleus

Question 9

Which process describes the movement of water across a selectively permeable membrane from an area of low solute concentration to high solute concentration?

Accepted Answer

Osmosis

Question 10

A cell engulfs a large bacterium by wrapping its plasma membrane around it and forming a vesicle. What is this process called?

Accepted Answer

Phagocytosis

Question 11

Which of the following best describes the role of the Golgi apparatus in the endomembrane system?

Accepted Answer

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

Question 12

Which of the following is a correct statement about the sodium-potassium pump ($\mathrm{Na^+/K^+}$ ATPase)?

Accepted Answer

It moves 3 $\mathrm{Na^+}$ ions out of the cell and 2 $\mathrm{K^+}$ ions into the cell per ATP hydrolyzed.

Question 13

Which organelle is primarily responsible for detoxifying harmful substances and synthesizing most of the cell's phospholipids?

Accepted Answer

Smooth endoplasmic reticulum (SER)

Question 14

A cell is placed in an isotonic solution. What will happen to the cell's volume, and why?

Accepted Answer

The cell's volume will remain unchanged because there is no net movement of water.

Question 15

Which of the following best describes the function of lysosomes?

Accepted Answer

They digest and recycle worn-out organelles and macromolecules.

Question 16

Which of the following is true regarding the fluid mosaic model of the plasma membrane?

Accepted Answer

The membrane is a dynamic structure with proteins and lipids able to move laterally within the bilayer.

Question 17

Which of the following best explains the difference between simple diffusion and facilitated diffusion?

Accepted Answer

Simple diffusion involves nonpolar molecules moving directly through the bilayer, while facilitated diffusion requires membrane proteins for polar or charged molecules.

Question 18

Which of the following best describes the role of peroxisomes in the cell?

Accepted Answer

They use oxygen to oxidize toxic substances, producing hydrogen peroxide ($\mathrm{H_2O_2}$) and breaking down fatty acids.

Question 19

A cell needs to import cholesterol from the extracellular fluid. Which transport mechanism is most likely involved?

Accepted Answer

Receptor-mediated endocytosis

Question 20

Which of the following best describes the function of ribosomes?

Accepted Answer

They are the site of protein synthesis, translating mRNA into polypeptides.

Introduction to Cells: Structure and Basic Processes

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