Question 1

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

Accepted Answer

A fluid structure with proteins embedded in or attached to a double layer of phospholipids.

Question 2

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

Accepted Answer

To maintain membrane fluidity at different temperatures.

Question 3

Which type of molecule can most easily diffuse directly through the phospholipid bilayer of a cell membrane?

Accepted Answer

Small nonpolar molecules such as O$$_2$$ and CO$$_2$$

Question 4

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

Accepted Answer

It will gain water and burst (lyse).

Question 5

Which of the following best explains why plant cells do not burst when placed in a hypotonic solution?

Accepted Answer

Their cell wall provides structural support and prevents excessive expansion.

Question 6

Which of the following statements about facilitated diffusion is correct?

Accepted Answer

It requires specific transport proteins but does not require energy.

Question 7

A cell actively transports Ca$$^{2+}$$ ions out of the cytoplasm. What does this indicate about the concentration of Ca$$^{2+}$$ inside and outside the cell?

Accepted Answer

Ca$$^{2+} is $$more concentrated outside the cell.

Question 8

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

Accepted Answer

Phagocytosis

Question 9

What is the main difference between simple diffusion and facilitated diffusion?

Accepted Answer

Facilitated diffusion requires transport proteins, while simple diffusion does not.

Question 10

A dialysis bag containing 0.4 M sucrose is placed in a beaker of pure water. The bag is permeable to water but not to sucrose. What will happen to the mass of the bag over time?

Accepted Answer

The bag will gain mass as water enters.

Question 11

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

Accepted Answer

They serve as identification tags recognized by other cells.

Question 12

Which equation correctly represents the direction of net water movement during osmosis?

Accepted Answer

$$	ext{Net water movement:} \quad 	ext{from low solute concentration} ightarrow 	ext{high solute concentration}$$

Question 13

Which of the following is an example of active transport?

Accepted Answer

Pumping Na$$^+$$ ions out of a neuron using ATP

Question 14

Which of the following statements about the formation of biological membranes is correct?

Accepted Answer

Phospholipids spontaneously form bilayers in water due to their amphipathic nature.

Question 15

A cell is placed in a 2% sucrose solution. The cytoplasm contains 0.5% sucrose. The membrane is not permeable to sucrose. What will happen?

Accepted Answer

Water will move out of the cell, causing it to shrink.

Question 16

Which of the following best describes receptor-mediated endocytosis?

Accepted Answer

The cell takes in specific molecules after they bind to receptors on the membrane.

Question 17

Which of the following is a function of membrane attachment proteins (integrins)?

Accepted Answer

They allow cells to attach to the cytoskeleton and extracellular matrix.

Question 18

Which of the following scenarios best illustrates selective permeability of the plasma membrane?

Accepted Answer

O$$_2$$ and CO$$_2$$ diffuse easily, but ions require transport proteins.

Question 19

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

Accepted Answer

Their kinks prevent phospholipids from packing closely together.

Question 20

During exocytosis, what happens to the plasma membrane?

Accepted Answer

It expands as vesicles fuse with it.

Membrane Structure and Function: Study Guide for General Biology

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