Question 1

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

Accepted Answer

A hydrophilic head and two hydrophobic tails

Question 2

What is the primary function of cholesterol in the plasma membrane?

Accepted Answer

It acts as a buffer, increasing or decreasing membrane fluidity depending on temperature

Question 3

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

Accepted Answer

Water will enter the cell, causing it to swell and possibly burst

Question 4

Which of the following best explains why unsaturated fatty acids increase membrane fluidity?

Accepted Answer

The double bonds create kinks, preventing tight packing of phospholipids

Question 5

Which equation best represents the process of simple diffusion across a membrane?

Accepted Answer

$$J = -D \frac{dC}{dx}$$

Question 6

A cell is placed in a solution where the concentration of solute outside the cell is higher than inside. What type of solution is this, and what is the expected movement of water?

Accepted Answer

Hypertonic; water will move out of the cell

Question 7

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

Accepted Answer

Storing genetic information

Question 8

Facilitated diffusion differs from simple diffusion in that facilitated diffusion:

Accepted Answer

Requires transport proteins but does not require energy

Question 9

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

Accepted Answer

A dynamic structure with proteins and lipids able to move laterally within the layer

Question 10

Which organelle is responsible for packaging proteins to be exported from the cell?

Accepted Answer

Golgi apparatus

Question 11

Which of the following statements about active transport is correct?

Accepted Answer

It requires energy and moves substances against their concentration gradient

Question 12

A scientist fuses a human cell and a mouse cell, each labeled with different fluorescent markers on their membrane proteins. Over time, the markers mix. What does this experiment demonstrate?

Accepted Answer

Membrane proteins are fluid and can move laterally within the bilayer

Question 13

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

Accepted Answer

Eukaryotic cells have internal membrane-bound organelles, while prokaryotic cells do not

Question 14

Which process is responsible for the passive movement of water across a selectively permeable membrane?

Accepted Answer

Osmosis

Question 15

Which of the following best describes the role of the cytoskeleton in eukaryotic cells?

Accepted Answer

It provides structural support and facilitates movement of organelles

Question 16

Which of the following is true about endocytosis?

Accepted Answer

It involves the plasma membrane engulfing material to bring it into the cell

Question 17

Which of the following best explains why channel proteins are necessary for the transport of certain molecules across the plasma membrane?

Accepted Answer

Some molecules are too large or polar to pass through the hydrophobic core of the lipid bilayer

Question 18

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

Accepted Answer

Mitochondrion

Question 19

Which of the following best describes the process of receptor-mediated endocytosis?

Accepted Answer

It selectively brings specific molecules into the cell by binding them to receptors on the membrane

Question 20

Which of the following statements about the nucleus is correct?

Accepted Answer

It stores and protects chromosomes and is the site of transcription

Cellular Membranes, Diffusion, and Organelles: Structure and Function

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