Question 1

Which of the following best describes the fluid mosaic model of the plasma membrane?

Accepted Answer

A dynamic structure with proteins and carbohydrates embedded in or attached to a bilayer of phospholipids.

Question 2

Which component of the plasma membrane is primarily responsible for its selective permeability?

Accepted Answer

Phospholipid bilayer

Question 3

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 moves into the cell by osmosis.

Question 4

Which of the following is a function of membrane carbohydrates?

Accepted Answer

Serving as recognition sites for cell-cell interactions

Question 5

Which type of membrane protein is covalently attached to fatty acids and can be released from the membrane by breaking these covalent bonds?

Accepted Answer

Lipid-anchored protein

Question 6

A nerve cell uses the sodium-potassium pump to maintain its resting potential. Which equation best represents the energy requirement for this process?

Accepted Answer

$$ \mathrm{Na^+/K^+-ATPase:} \ 3\ Na^+_{out} + 2\ K^+_{in} + ATP \rightarrow 3\ Na^+_{out} + 2\ K^+_{in} + ADP + P_i $$

Question 7

Which of the following best explains why ions such as $$ Na^+ $$ and $$ K^+ $$ cannot freely diffuse across the plasma membrane?

Accepted Answer

They are hydrophilic and charged, so they cannot pass through the hydrophobic core of the lipid bilayer.

Question 8

Which of the following is an example of secondary active transport?

Accepted Answer

Uptake of glucose into intestinal cells via a sodium-glucose symporter, using the $$ Na^+ $$ gradient established by the $$ Na^+/K^+ $$ pump

Question 9

Which of the following best describes the role of cadherins in cell adhesion?

Accepted Answer

They mediate homotypic binding between cells, allowing similar cells to adhere to each other.

Question 10

A mutation causes a cell to lack functional clathrin. Which process would be most directly affected?

Accepted Answer

Receptor-mediated endocytosis

Question 11

Which of the following statements about the extracellular matrix (ECM) in animal cells is correct?

Accepted Answer

Collagen and elastin are major structural proteins in the ECM, providing strength and elasticity.

Question 12

Which of the following best describes the function of tight junctions in epithelial tissues?

Accepted Answer

They prevent the leakage of extracellular fluid across a layer of epithelial cells.

Question 13

A plant cell is placed in a hypertonic solution. What is the most likely outcome, and which term describes the resulting condition?

Accepted Answer

The cell will lose water and the plasma membrane will pull away from the cell wall; this is called plasmolysis.

Question 14

Which of the following is NOT a function of biological membranes?

Accepted Answer

Synthesis of DNA

Question 15

Which of the following best explains why facilitated diffusion is necessary for glucose transport into most animal cells?

Accepted Answer

Glucose is polar and too large to pass through the hydrophobic core of the membrane without a transport protein.

Question 16

Which of the following best describes the difference between primary and secondary active transport?

Accepted Answer

Primary active transport uses ATP directly, while secondary active transport uses the energy stored in an ion gradient.

Question 17

Which of the following is a correct statement about plasmodesmata in plant cells?

Accepted Answer

They are channels that allow direct cytoplasmic exchange between adjacent plant cells.

Question 18

Which of the following best describes the process of exocytosis?

Accepted Answer

The fusion of a vesicle with the plasma membrane to release its contents outside the cell.

Question 19

Which of the following best explains why cholesterol is important in animal cell membranes?

Accepted Answer

It modulates membrane fluidity and stability across temperature changes.

Question 20

Which of the following is a real-life example of receptor-mediated endocytosis?

Accepted Answer

Uptake of low-density lipoprotein (LDL) cholesterol by liver cells.

Cellular Membranes: Structure, Function, and Composition

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