$$\text{Water moves from high water concentration to low water concentration across a selectively permeable membrane}$$

Question 1

Which structural feature is common to all lipids, making them hydrophobic?

Accepted Answer

Long chains of carbon and hydrogen atoms with nonpolar covalent bonds

Question 2

A patient is found to have abnormally rigid cell membranes at low temperatures. Which molecule is most likely deficient in their membranes?

Accepted Answer

Cholesterol

Question 3

Which of the following best describes the structure of a steroid molecule?

Accepted Answer

Four interlocking carbon rings with various functional groups attached

Question 4

Which type of lipid is primarily responsible for forming the main structure of cell membranes?

Accepted Answer

Phospholipids

Question 5

A triglyceride is synthesized by joining three fatty acids to a glycerol molecule. What type of reaction is this?

Accepted Answer

Dehydration synthesis

Question 6

Which of the following statements about saturated and unsaturated fatty acids is correct?

Accepted Answer

Unsaturated fatty acids have one or more double bonds, causing kinks in the chain

Question 7

Trans fats are produced by hydrogenating unsaturated fats. What is a major health risk associated with consuming trans fats?

Accepted Answer

Increased risk of heart attack

Question 8

Which of the following best explains why phospholipids form bilayers in water?

Accepted Answer

Their hydrophilic heads interact with water, while hydrophobic tails avoid it

Question 9

A cell is placed in a solution with a higher solute concentration than its cytoplasm. What will happen to the cell?

Accepted Answer

It will shrink as water leaves

Question 10

Which equation correctly represents the process of osmosis?

Accepted Answer

$$	ext{Water moves from high water concentration to low water concentration across a selectively permeable membrane}$$

Question 11

Which factor would most likely increase the permeability of a cell membrane?

Accepted Answer

Increasing the number of double bonds in fatty acid tails

Question 12

Which type of membrane protein is responsible for moving substances against their concentration gradient, and what energy source does it use?

Accepted Answer

Active transporter; uses ATP

Question 13

A plant cell is placed in a hypotonic solution. What is the expected outcome?

Accepted Answer

The cell will become turgid (normal)

Question 14

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

Accepted Answer

A dynamic structure with various proteins, lipids, and carbohydrates that can move laterally

Question 15

Which membrane protein type is most likely to be involved in cell recognition and immune response?

Accepted Answer

Glycoprotein

Question 16

Which of the following factors would decrease the rate of diffusion across a cell membrane?

Accepted Answer

Decreasing the concentration gradient

Question 17

Which equation best describes the relationship between diffusion rate and concentration gradient?

Accepted Answer

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

Question 18

Which of the following is a function of membrane attachment proteins?

Accepted Answer

Anchoring the cell to the extracellular matrix or cytoskeleton

Question 19

A cell is placed in an isotonic solution. What will happen to the cell?

Accepted Answer

Water will move in and out equally, and the cell will remain the same size

Question 20

Which of the following best explains why cholesterol is important in animal cell membranes?

Accepted Answer

It stabilizes membrane fluidity and decreases permeability, especially at varying temperatures

Lipids and Cell Membranes: Structure, Function, and Transport

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