Question 1

Which of the following best explains why phospholipids form bilayers in aqueous environments?

Accepted Answer

Their amphipathic nature causes hydrophobic tails to avoid water and hydrophilic heads to interact with water.

Question 2

A scientist observes that a cell membrane becomes more rigid at lower temperatures. Which change in membrane composition would most likely increase its fluidity under these conditions?

Accepted Answer

Increasing the proportion of unsaturated fatty acids.

Question 3

Which of the following molecules would most easily diffuse across a pure phospholipid bilayer without the help of a protein transporter?

Accepted Answer

O$$_2$$

Question 4

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

Accepted Answer

It will swell and possibly burst because water will move into the cell by osmosis.

Question 5

Which of the following best describes the relationship between passive transport and dynamic equilibrium?

Accepted Answer

Passive transport allows molecules to move down their concentration gradient until dynamic equilibrium is achieved.

Question 6

Which of the following statements about cholesterol in animal cell membranes is correct?

Accepted Answer

Cholesterol decreases membrane fluidity at high temperatures and increases it at low temperatures.

Question 7

Which of the following is a key structural difference between prokaryotic and eukaryotic cells?

Accepted Answer

Eukaryotic cells contain membrane-bound organelles, while prokaryotic cells do not.

Question 8

A protein destined for secretion from a eukaryotic cell follows which general pathway?

Accepted Answer

Rough ER → Golgi apparatus → vesicle → plasma membrane

Question 9

Which of the following organelles is responsible for ATP production in eukaryotic cells?

Accepted Answer

Mitochondrion

Question 10

Which process involves the engulfment of large particles by the cell membrane to form an internal vesicle?

Accepted Answer

Phagocytosis

Question 11

A cell is observed to have a cell wall, chloroplasts, and a large central vacuole. Which type of cell is this most likely to be?

Accepted Answer

Plant cell

Question 12

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

Accepted Answer

Modifies, sorts, and packages proteins and lipids for secretion or delivery to other organelles

Question 13

Which of the following statements about the cytoskeleton is correct?

Accepted Answer

It provides structural support, aids in cell movement, and helps transport materials within the cell.

Question 14

Which of the following best explains why ions such as Na$$^+$$ and Cl$$^-$$ cannot easily cross the lipid bilayer?

Accepted Answer

They are charged and cannot pass through the hydrophobic core of the bilayer.

Question 15

Which of the following is a function of the smooth endoplasmic reticulum (smooth ER)?

Accepted Answer

Lipid synthesis and detoxification

Question 16

A cell is placed in a solution and water moves into the cell, causing it to swell. Which equation best describes the osmotic movement of water?

Accepted Answer

$$\Psi_{water}$$ moves from high to low water potential

Question 17

Which of the following is true about receptor-mediated endocytosis compared to simple endocytosis?

Accepted Answer

Receptor-mediated endocytosis allows the cell to selectively take up specific molecules from the environment.

Question 18

Which of the following best describes the role of transmembrane proteins in the plasma membrane?

Accepted Answer

They allow selective transport of specific molecules across the membrane.

Question 19

Which of the following is NOT a component of the endomembrane system?

Accepted Answer

Mitochondria

Question 20

A mutation causes a cell to lack functional lysosomes. Which of the following would most likely result?

Accepted Answer

The cell would accumulate undigested waste and damaged organelles.

Lipids, Cell Membranes, and Cell Structure: Study Guide for BIOL 208

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