Q: Which equation best represents the movement of water during osmosis across a selectively permeable membrane?

$$ \text{Water moves from regions of low solute concentration to high solute concentration} $$

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

A researcher adds cholesterol to a sample of artificial phospholipid bilayers. What is the most likely effect on the membrane's permeability?

Accepted Answer

Permeability will decrease because cholesterol increases the packing density of the hydrophobic tails.

Question 3

Which of the following statements about membrane proteins is correct according to the fluid-mosaic model?

Accepted Answer

Integral membrane proteins can span the membrane and have regions exposed to both the interior and exterior of the cell.

Question 4

A cell is placed in a hypertonic solution. What will happen to the cell and why?

Accepted Answer

Water will move out of the cell, causing it to shrink, because the solute concentration is higher outside the cell.

Question 5

Which of the following best describes the difference between saturated and unsaturated fatty acids?

Accepted Answer

Saturated fatty acids have only single bonds between carbons, while unsaturated fatty acids have one or more double bonds.

Question 6

Which equation best represents the movement of water during osmosis across a selectively permeable membrane?

Accepted Answer

$$ 	ext{Water moves from regions of low solute concentration to high solute concentration} $$

Question 7

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

Accepted Answer

The membrane will become less fluid and less permeable.

Question 8

Which of the following is a function of membrane proteins that cannot be performed by phospholipids alone?

Accepted Answer

Facilitating the transport of specific ions and polar molecules across the membrane.

Question 9

Which of the following best explains why facilitated diffusion does not require energy input?

Accepted Answer

It moves substances down their concentration gradient with the help of membrane proteins.

Question 10

The sodium-potassium pump (Na+/K+-ATPase) is an example of which type of membrane transport?

Accepted Answer

Active transport

Question 11

Which of the following statements about the permeability of lipid bilayers is correct?

Accepted Answer

Small nonpolar molecules cross the bilayer quickly, while large polar molecules cross slowly.

Question 12

A scientist creates a planar bilayer with short, unsaturated hydrocarbon tails. Which of the following is most likely true about this membrane?

Accepted Answer

It will have high permeability to solutes.

Question 13

Which of the following best describes the role of ATP in active transport?

Accepted Answer

ATP provides energy by transferring a phosphate group to the transport protein.

Question 14

Which of the following is a real-world example of a disease caused by a defect in a membrane protein channel?

Accepted Answer

Cystic fibrosis, caused by a defective chloride ion channel (CFTR)

Question 15

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

Accepted Answer

It uses the energy stored in an electrochemical gradient to move another molecule against its gradient.

Question 16

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

Accepted Answer

Forming the primary structure of DNA

Question 17

A vesicle containing nucleic acids is placed in a solution with a higher solute concentration than inside the vesicle. What will happen to the vesicle?

Accepted Answer

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

Question 18

Which of the following best explains why phospholipids are considered amphipathic molecules?

Accepted Answer

They contain both hydrophilic and hydrophobic regions.

Question 19

Which of the following would most likely increase the fluidity of a cell membrane at low temperatures?

Accepted Answer

Increasing the proportion of unsaturated fatty acids in the phospholipids

Lipids, Membranes, and the First Cells – Chapter 6 Study Notes

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