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 structure where proteins bob in a fluid phospholipid bilayer, with both lipids and proteins able to move laterally.

Question 2

Which of the following molecules would most easily diffuse through a pure phospholipid bilayer without the aid of a transport protein?

Accepted Answer

Oxygen (O2)

Question 3

A red blood cell is placed in a solution and swells until it bursts. Which of the following best describes the tonicity of the solution relative to the cell?

Accepted Answer

Hypotonic

Question 4

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

Accepted Answer

Cholesterol decreases membrane fluidity at low temperatures by preventing tight packing.

Question 5

Which process requires energy input in the form of ATP to move molecules across the plasma membrane?

Accepted Answer

Active transport

Question 6

A plant cell is placed in a hypertonic solution. What will most likely happen to the cell?

Accepted Answer

It will undergo plasmolysis, causing the membrane to pull away from the cell wall.

Question 7

Which of the following best explains why glucose carrier proteins do not transport fructose across the plasma membrane?

Accepted Answer

Carrier proteins are specific to the shape and chemical properties of their substrate.

Question 8

Which of the following is a function of membrane proteins?

Accepted Answer

Facilitating cell-cell recognition

Question 9

The sodium-potassium pump is an example of which type of membrane transport?

Accepted Answer

Active transport

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

Which of the following best describes receptor-mediated endocytosis?

Accepted Answer

The cell selectively takes in specific molecules that bind to receptors on the plasma membrane.

Question 12

Which of the following is true about the movement of ions across a membrane?

Accepted Answer

Ions move according to their electrochemical gradient, which includes both concentration and electrical forces.

Question 13

Which of the following is a real-world example of cotransport in human physiology?

Accepted Answer

The Na+/glucose transporter in the intestine absorbing glucose from food.

Question 14

Which of the following statements about facilitated diffusion is correct?

Accepted Answer

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

Question 15

A patient with familial hypercholesterolemia has high blood cholesterol because:

Accepted Answer

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

Question 16

Which of the following best explains why winter wheat increases the percentage of unsaturated phospholipids in its membranes during autumn?

Accepted Answer

To maintain membrane fluidity at lower temperatures.

Question 17

Which of the following is NOT a function of cell-surface membrane proteins?

Accepted Answer

Synthesis of DNA

Question 18

Which of the following best describes the role of aquaporins in the plasma membrane?

Accepted Answer

They provide a hydrophilic channel for rapid water movement across the membrane.

Question 19

Which of the following is true regarding the sidedness (asymmetry) of the plasma membrane?

Accepted Answer

The inside and outside faces of the membrane have distinct compositions of proteins, lipids, and carbohydrates.

Question 20

Which of the following equations best represents the movement of water during osmosis?

Accepted Answer

$$ 	ext{Water moves from a region of lower solute concentration to a region of higher solute concentration across a selectively permeable membrane} $$

Chapter 7: Membrane Structure and Function: Study Guide

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