Question 1

Which of the following best explains why lipids are not considered polymers, even though they are large macromolecules?

Accepted Answer

Lipids are not made from repeating monomer units joined by covalent bonds.

Question 2

Which property is unique to lipids compared to carbohydrates, proteins, and nucleic acids?

Accepted Answer

Lipids are primarily hydrophobic and do not dissolve in water.

Question 3

A fatty acid and a lipid interact with water differently. Which statement best describes this difference?

Accepted Answer

Fatty acids have a hydrophilic carboxyl group that can interact with water, while most lipids are largely hydrophobic.

Question 4

Which of the following best describes the arrangement of phospholipids in a biological membrane?

Accepted Answer

Hydrophilic heads face outward toward water, and hydrophobic tails face inward, away from water.

Question 5

Why does the degree of saturation in phospholipid fatty acid tails affect membrane fluidity?

Accepted Answer

Unsaturated fatty acids have kinks that prevent tight packing, increasing fluidity.

Question 6

How does cholesterol affect the fluidity of animal cell membranes at normal physiological temperatures?

Accepted Answer

Cholesterol reduces membrane fluidity by restricting the movement of phospholipids.

Question 7

Which of the following best defines an amphipathic molecule?

Accepted Answer

A molecule that has both hydrophilic and hydrophobic regions.

Question 8

A red blood cell is placed in a hypotonic solution. What will happen to the cell, and which process is responsible?

Accepted Answer

Water will enter the cell by osmosis, causing it to swell and possibly burst.

Question 9

Which of the following best describes facilitated diffusion?

Accepted Answer

Movement of molecules down their concentration gradient through a membrane protein, without energy input.

Question 10

Which equation correctly represents the calculation of osmolarity ($$O) $$for a solution?

Accepted Answer

$$O = M 	imes n$$

Question 11

A cell uses a protein pump to move sodium ions ($$Na^+) $$from a region of low concentration to high concentration. Which type of transport is this?

Accepted Answer

Active transport

Question 12

Which of the following statements about selective permeability of the plasma membrane is correct?

Accepted Answer

The membrane allows some substances to cross more easily than others due to the chemical properties of phospholipids and proteins.

Question 13

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

Accepted Answer

A dynamic structure with proteins embedded in or attached to a bilayer of phospholipids.

Question 14

Which type of membrane protein forms a hydrophilic channel that allows specific molecules or ions to cross the membrane?

Accepted Answer

Channel protein

Question 15

A solution has a higher solute concentration than the cytoplasm of a cell. What term describes this solution, and what will happen to the cell?

Accepted Answer

Hypertonic; the cell will lose water and shrink.

Question 16

Which process does NOT require energy input from the cell?

Accepted Answer

Passive transport

Question 17

Which of the following is a real-life example of facilitated diffusion?

Accepted Answer

Glucose entering a muscle cell through a GLUT transporter.

Question 18

Which statement best explains why transmembrane proteins are necessary for the transport of certain molecules across the plasma membrane?

Accepted Answer

Some molecules are too large or polar to pass through the hydrophobic core of the lipid bilayer.

Question 19

Which of the following best describes osmosis?

Accepted Answer

The movement of water across a selectively permeable membrane from low solute concentration to high solute concentration.

Lipids, Membranes, and Transport: Key Concepts in General Biology

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