Question 1

Which of the following statements about all lipids is correct?

Accepted Answer

All lipids do not dissolve in water.

Question 2

Which type of fat would you expect to be solid at room temperature?

Accepted Answer

Fats containing primarily saturated fatty acids

Question 3

Which of the following best describes the structure of a phospholipid?

Accepted Answer

A nonpolar lipid molecule that is made amphipathic by the addition of a phosphate

Question 4

What structural feature of phospholipids allows them to form bilayers in water?

Accepted Answer

They have polar heads and nonpolar tails; the polar heads interact with water.

Question 5

Which of the following changes would increase the fluidity and permeability of a phospholipid bilayer?

Accepted Answer

Replacing saturated fatty acids with unsaturated fatty acids

Question 6

A cell membrane is composed of phospholipids with long, saturated hydrocarbon tails. What effect does this have on membrane properties?

Accepted Answer

It decreases membrane permeability and fluidity.

Question 7

Which of the following factors would decrease membrane fluidity?

Accepted Answer

All of the above

Question 8

A vesicle containing pure water is placed in a solution with a high concentration of solutes. What will happen to the vesicle?

Accepted Answer

Net flow of water out of the vesicle

Question 9

A patient receives a transfusion of distilled water equal to the volume of blood lost. What is the most probable result?

Accepted Answer

The patient's red blood cells will swell and possibly burst because the blood has become hypotonic compared to the cells.

Question 10

Which of the following best explains how ions and other charged molecules cross cell membranes?

Accepted Answer

They cross through proteins embedded in the membrane.

Question 11

Which of the following is a function of the sodium-potassium pump in animal cells?

Accepted Answer

It uses ATP to move sodium and potassium ions against their concentration gradients.

Question 12

Which of the following would be used for moving glucose from a low concentration on the outside of a cell to a high concentration on the inside?

Accepted Answer

Active transport

Question 13

At equilibrium, for a molecule that can diffuse across a lipid bilayer, which of the following is true?

Accepted Answer

There is no change in the concentration of the molecule on either side of the membrane.

Question 14

Which of the following best describes the selectivity of an ion channel?

Accepted Answer

It permits passage only to a specific ion.

Question 15

Which of the following is NOT a category of lipids?

Accepted Answer

Nucleic acids

Question 16

Which of the following molecules would have the highest permeability through a pure phospholipid bilayer?

Accepted Answer

Carbon dioxide ($CO_2$)

Question 17

If you replace all saturated fatty acids in a membrane with unsaturated fatty acids, what is the expected effect on the membrane's permeability to $CO_2$?

Accepted Answer

Increased permeability to $CO_2$

Question 18

Which of the following best describes the amphipathic nature of phospholipids?

Accepted Answer

They have both hydrophilic and hydrophobic regions.

Question 19

A dialysis bag is filled with a 0.2 M sucrose solution and placed in a beaker containing 0.6 M sucrose. The membrane is permeable to water but not sucrose. What will happen?

Accepted Answer

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

Question 20

Which of the following is a real-life example of the consequences of osmosis in medical practice?

Accepted Answer

Administering distilled water intravenously can cause red blood cells to swell and burst due to osmosis.

Lipids and Membranes: Structure, Function, and Biological Roles

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