Q: Which of the following equations correctly represents the hydrolysis of ATP, which powers active transport?

$$ \mathrm{ATP} + \mathrm{H}_2\mathrm{O} \rightarrow \mathrm{ADP} + \mathrm{P}_i + \text{energy} $$

Question 1

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

Accepted Answer

A dynamic bilayer of phospholipids with proteins bobbing in the fluid matrix, often forming functional groups.

Question 2

Which of the following adaptations would you expect to find in the cell membranes of fish living in extremely cold environments?

Accepted Answer

A high proportion of unsaturated fatty acids in membrane phospholipids.

Question 3

Which of the following statements about membrane proteins is correct?

Accepted Answer

Transmembrane proteins are a type of integral protein that span the entire membrane.

Question 4

A patient with familial hypercholesterolemia has high blood cholesterol because:

Accepted Answer

Their cells have defective or missing LDL receptor proteins, preventing cholesterol uptake.

Question 5

Which of the following molecules would most easily diffuse through a pure phospholipid bilayer?

Accepted Answer

Oxygen (O₂)

Question 6

What is the main function of cholesterol in animal cell membranes at low temperatures?

Accepted Answer

It prevents tight packing of phospholipids, maintaining membrane fluidity.

Question 7

Which process is responsible for the uptake of large particles, such as bacteria, by white blood cells?

Accepted Answer

Phagocytosis

Question 8

A nerve cell responds to a stimulus by opening potassium ion channels. This is an example of:

Accepted Answer

Facilitated diffusion through gated channels

Question 9

Which of the following best explains why sodium-potassium pumps are essential for animal cells?

Accepted Answer

They maintain the electrochemical gradient by actively transporting Na⁺ out and K⁺ into the cell using ATP.

Question 10

Which of the following equations correctly represents the hydrolysis of ATP, which powers active transport?

Accepted Answer

$$ \mathrm{ATP} + \mathrm{H}_2\mathrm{O} ightarrow \mathrm{ADP} + \mathrm{P}_i + 	ext{energy} $$

Question 11

A plant cell is placed in a solution with a higher concentration of sucrose than inside the cell. Which process will most likely occur to move sucrose into the cell?

Accepted Answer

Active transport via a cotransporter coupled to proton diffusion

Question 12

Which of the following is a real-life medical application of membrane protein specificity?

Accepted Answer

Using drugs to mask the CCR5 co-receptor to prevent HIV from entering immune cells.

Question 13

Which of the following statements about facilitated diffusion is correct?

Accepted Answer

It uses transport proteins to move substances down their concentration gradient.

Question 14

Which of the following best describes the role of glycoproteins and glycolipids in the plasma membrane?

Accepted Answer

They serve as markers for cell recognition and identification.

Question 15

A person suffering from severe diarrhea is given a solution containing both NaCl and glucose. Why is this treatment effective?

Accepted Answer

Glucose and Na⁺ are absorbed together via cotransporters, restoring sodium levels in the body.

Question 16

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

Accepted Answer

Synthesis of DNA

Question 17

Which of the following best explains why hydrophobic molecules pass more easily through the plasma membrane than hydrophilic molecules?

Accepted Answer

Hydrophobic molecules dissolve in the lipid bilayer, while hydrophilic molecules are repelled by the hydrophobic core.

Question 18

Which of the following is an example of bulk transport?

Accepted Answer

Exocytosis of insulin from pancreatic cells

Question 19

Which equation best represents the electrochemical gradient that drives ion movement across membranes?

Accepted Answer

$$ \Delta G = RT \ln \left( \frac{[	ext{ion}]_{	ext{inside}}}{[	ext{ion}]_{	ext{outside}}} ight) + zF\Delta \Psi $$

Membrane Structure and Function – Study Notes (Campbell Biology, Ch. 7)

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