Question 1

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

Accepted Answer

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

Question 2

Which of the following statements about membrane permeability is correct?

Accepted Answer

Membranes with more cholesterol are less permeable to small molecules.

Question 3

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

Accepted Answer

The cells will shrink as water leaves them.

Question 4

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

Accepted Answer

It decreases membrane permeability by increasing the packing density of phospholipid tails.

Question 5

Which of the following molecules would diffuse most rapidly across a pure phospholipid bilayer?

Accepted Answer

Oxygen ($$O_2)$$

Question 6

A mutation causes a cell to produce phospholipids with much longer hydrocarbon tails. What is the most likely effect on the cell membrane?

Accepted Answer

The membrane will become less fluid and less permeable.

Question 7

Which of the following is a key difference between facilitated diffusion and active transport?

Accepted Answer

Active transport requires energy input, often from ATP, while facilitated diffusion does not.

Question 8

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

Accepted Answer

They have both a hydrophilic head and a hydrophobic tail.

Question 9

A cell is placed in a hypotonic solution. What will happen to the cell?

Accepted Answer

Water will move into the cell, causing it to swell.

Question 10

Which of the following is NOT a function of lipids in biological systems?

Accepted Answer

Serving as enzymes for chemical reactions

Question 11

Which of the following statements about the sodium-potassium pump is correct?

Accepted Answer

It requires ATP to function.

Question 12

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

Accepted Answer

Their double bonds create kinks, preventing tight packing of tails.

Question 13

Which of the following is a correct description of a steroid?

Accepted Answer

A lipid with a bulky, four-ring structure and variable functional groups.

Question 14

Which experimental system is used to study the permeability of artificial membranes?

Accepted Answer

Planar bilayers

Question 15

Which of the following is true about the fluid-mosaic model of membrane structure?

Accepted Answer

Proteins and phospholipids move laterally within the membrane.

Question 16

A person with cystic fibrosis has a defect in which type of membrane protein?

Accepted Answer

A transmembrane protein that allows chloride ions to pass

Question 17

Which of the following best describes secondary active transport (co-transport)?

Accepted Answer

It relies on electrochemical gradients established by primary active transport.

Question 18

Which of the following is a property of amphipathic proteins that allows them to be embedded in membranes?

Accepted Answer

They have both hydrophilic and hydrophobic regions.

Question 19

Which of the following is a real-world example of selective permeability in action?

Accepted Answer

Oxygen entering red blood cells rapidly, while glucose enters slowly.

Question 20

Which of the following best explains why lipids are insoluble in water?

Accepted Answer

They contain a high proportion of nonpolar bonds.

Lipids, Membranes, and the First Cells: Structure, Function, and Transport

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