Question 1

Which of the following best describes the structure of a phospholipid molecule in the plasma membrane?

Accepted Answer

A hydrophilic head and two hydrophobic tails

Question 2

According to the fluid mosaic model, which statement is correct about the movement of membrane components?

Accepted Answer

Most lipids and some proteins can move laterally within the membrane

Question 3

A cell is exposed to decreasing temperatures. Which adaptation would help maintain membrane fluidity?

Accepted Answer

Increase the proportion of unsaturated phospholipids and cholesterol in the membrane

Question 4

Which of the following molecules can pass through the plasma membrane without the help of transport proteins?

Accepted Answer

Oxygen ($$O_2)$$

Question 5

What is the main difference between passive diffusion and facilitated diffusion across a cell membrane?

Accepted Answer

Facilitated diffusion requires transport proteins, while passive diffusion does not

Question 6

A red blood cell is placed in a hypertonic solution. What is the most likely outcome?

Accepted Answer

The cell will lose water and shrink

Question 7

Which of the following best describes the function of the sodium-potassium pump ($$Na^+/K^+$$ pump) in animal cells?

Accepted Answer

It uses ATP to move $$Na^+$$ out of the cell and $$K^+$$ into the cell, both against their concentration gradients

Question 8

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

Accepted Answer

Synthesis of DNA

Question 9

A cell is placed in a solution with a lower solute concentration than the cytoplasm. What type of solution is this, and what will happen to the cell?

Accepted Answer

Hypotonic; the cell will gain water

Question 10

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

Accepted Answer

Osmosis

Question 11

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

Accepted Answer

They are charged and hydrophilic, so they require transport proteins to cross the hydrophobic core of the membrane

Question 12

Which of the following is an example of receptor-mediated endocytosis?

Accepted Answer

A cell taking in cholesterol by binding LDL particles to specific receptors

Question 13

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

Accepted Answer

Cholesterol helps maintain membrane fluidity at both high and low temperatures

Question 14

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

Accepted Answer

They are involved in cell-cell recognition and signaling

Question 15

A scientist observes that a certain molecule moves across the plasma membrane only when a specific protein is present, and the process does not require ATP. What type of transport is this?

Accepted Answer

Facilitated diffusion

Question 16

Which of the following best describes the three stages of cell signaling?

Accepted Answer

Reception, transduction, response

Question 17

A cell uses a proton pump to create a high concentration of $$H^+$$ ions outside the membrane. What is this an example of?

Accepted Answer

Active transport creating an electrochemical gradient

Question 18

Which of the following scenarios best illustrates co-transport in a cell membrane?

Accepted Answer

A glucose molecule is transported into the cell along with a sodium ion ($$Na^+) $$using the energy from the sodium gradient

Question 19

Which of the following is a real-world example of the importance of membrane carbohydrates in human health?

Accepted Answer

Blood type (A, B, AB, O) is determined by specific carbohydrates on red blood cell membranes

Question 20

A patient is found to be resistant to HIV infection due to a genetic deficiency in the CCR5 protein. What is the most likely explanation for this resistance?

Accepted Answer

HIV cannot bind to the cell surface and enter the cell without the CCR5 co-receptor

Biology 130: Chapter 7 – Cell Membranes Study Guide

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