Question 1

Which of the following best describes the amphipathic nature of phospholipids and its significance in membrane structure?

Accepted Answer

Phospholipids have both hydrophilic heads and hydrophobic tails, allowing them to form bilayers in aqueous environments.

Question 2

A red blood cell is placed in a solution with an effective osmolarity lower than its cytoplasm. What will happen to the cell, and why?

Accepted Answer

The cell will swell and may burst because water moves into the cell by osmosis.

Question 3

Which of the following factors would increase the fluidity of a cell membrane?

Accepted Answer

Increasing the proportion of unsaturated fatty acids in phospholipids.

Question 4

Which equation correctly represents the relationship between osmotic pressure ($$\Pi$$), solute concentration ($$C$$), the gas constant ($$R$$), and temperature ($$T$$)?

Accepted Answer

$$\Pi = CRT$$

Question 5

A mutation causes a cell to produce only saturated fatty acids in its membrane phospholipids. What is the most likely effect on the cell membrane at low temperatures?

Accepted Answer

The membrane will become more rigid and less fluid, potentially impairing function.

Question 6

Which of the following best explains why ions such as $$\mathrm{Na^+}$$ and $$\mathrm{K^+}$$ cannot cross the phospholipid bilayer by simple diffusion?

Accepted Answer

They are charged and hydrophilic, so they cannot pass through the hydrophobic core of the bilayer.

Question 7

Which of the following statements about the fluid mosaic model is correct?

Accepted Answer

Membrane proteins and lipids can move laterally within the layer, but rarely flip-flop between layers.

Question 8

A patient is given an intravenous solution that is hypertonic relative to their red blood cells. What is the expected outcome for the red blood cells?

Accepted Answer

The cells will shrink as water leaves the cells by osmosis.

Question 9

Which of the following is a function of membrane glycoproteins?

Accepted Answer

Cell recognition and communication.

Question 10

Which of the following best describes the role of cholesterol in animal cell membranes at physiological temperature?

Accepted Answer

It acts as a fluidity buffer, resisting drastic changes in membrane fluidity.

Question 11

Which of the following transport processes requires cellular energy (ATP) and moves substances against their concentration gradient?

Accepted Answer

Primary active transport

Question 12

A cell needs to import large quantities of cholesterol from the bloodstream. Which process is most likely used?

Accepted Answer

Receptor-mediated endocytosis

Question 13

Which of the following best explains why glucose requires a transporter to cross the plasma membrane?

Accepted Answer

Glucose is a large, polar molecule and cannot diffuse through the hydrophobic core of the bilayer.

Question 14

Which of the following is true regarding the movement of water across cell membranes?

Accepted Answer

Water moves by osmosis from areas of high 'free' water concentration to areas of low 'free' water concentration.

Question 15

Which of the following best describes the effect of increasing temperature on membrane fluidity?

Accepted Answer

Increasing temperature increases membrane fluidity.

Question 16

Which of the following is a correct statement about facilitated diffusion?

Accepted Answer

It requires a transporter protein but does not require cellular energy.

Question 17

Which of the following is a real-life example of secondary active transport in animal cells?

Accepted Answer

Glucose absorption in the intestine using the sodium gradient.

Question 18

Which of the following best explains why plant cells do not burst in hypotonic solutions?

Accepted Answer

The cell wall provides structural support and resists excessive expansion.

Question 19

Which of the following statements about membrane proteins is correct?

Accepted Answer

Integral proteins span the membrane and have hydrophobic regions embedded in the bilayer.

Cell Membrane Structure and Function: Mini-Textbook Study Notes

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