Question 1

Which of the following best describes the amphipathic nature of phospholipids in biological membranes?

Accepted Answer

Phospholipids have a hydrophilic (polar) head and two hydrophobic (non-polar) tails.

Question 2

The Fluid Mosaic Model of the membrane states that:

Accepted Answer

Membranes are dynamic structures with proteins, lipids, and carbohydrates that can move laterally within the bilayer.

Question 3

Which of the following is a function of the plasma membrane?

Accepted Answer

It compartmentalizes the cell by forming organelles and maintains the intracellular environment.

Question 4

Steroids, such as cholesterol, are important in eukaryotic membranes because they:

Accepted Answer

Decrease membrane fluidity at high temperatures and increase it at low temperatures.

Question 5

Which equation best represents the formation of a triglyceride (fat) from its components?

Accepted Answer

$\mathrm{Glycerol} + 3\ \mathrm{Fatty\ acids} \rightarrow \mathrm{Triglyceride} + 3\ \mathrm{H_2O}$

Question 6

A cell membrane is described as 'semi-permeable.' What does this mean in terms of molecular transport?

Accepted Answer

Some molecules can pass through the membrane while others are blocked, depending on size, polarity, and charge.

Question 7

Feedback inhibition in metabolic pathways is best described as:

Accepted Answer

The inhibition of an enzyme early in the pathway by the final product, preventing overproduction.

Question 8

Which of the following statements about membrane asymmetry is correct?

Accepted Answer

The extracellular and cytosolic sides of the membrane have different types of phospholipids, which is important for membrane function.

Question 9

Which property of phospholipids allows them to spontaneously form bilayers in water?

Accepted Answer

Their hydrophobic tails repel water, while their hydrophilic heads interact with water.

Question 10

A mutation causes a cell to produce phospholipids with only saturated fatty acid tails. What effect would this likely have on the cell membrane?

Accepted Answer

The membrane would become less fluid and more rigid.

Question 11

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

Accepted Answer

Storing genetic information.

Question 12

Which of the following best explains why cells can change shape and increase surface area by adding new membrane lipids?

Accepted Answer

Membrane lipids are fluid and can move laterally, allowing the membrane to expand.

Question 13

Which of the following is a correct statement about the diversity of membrane lipids?

Accepted Answer

Membrane lipids vary in head groups, tail length, saturation, and sterol content, affecting membrane properties.

Question 14

Which of the following is a real-world example of membrane compartmentalization increasing cellular efficiency?

Accepted Answer

The presence of mitochondria in eukaryotic cells allows for efficient ATP production.

Question 15

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

Accepted Answer

Cholesterol stabilizes membrane fluidity across temperature changes.

Question 16

Which of the following is a consequence of the membrane's ability to create ion gradients?

Accepted Answer

Cells can generate electrical signals, as seen in neurons.

Question 17

Which of the following is true about the structure of a phospholipid bilayer?

Accepted Answer

The hydrophilic heads face the aqueous environment, while the hydrophobic tails face inward.

Question 18

Which of the following is a correct application of feedback inhibition in a metabolic pathway?

Accepted Answer

The final product of glycolysis inhibits the first enzyme in the glycolytic pathway.

Question 19

Which of the following best explains why phospholipids form bilayers rather than micelles in biological membranes?

Accepted Answer

Phospholipids have two hydrophobic tails, which makes bilayer formation energetically favorable.

Question 20

A researcher observes that a cell membrane contains a high proportion of unsaturated fatty acids. What property will this membrane likely exhibit?

Accepted Answer

Increased fluidity and decreased rigidity.

Lipids, Membranes, and Membrane Transport: Structure and Function

Study Guide - Practice Questions