Question 1

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

Accepted Answer

They contain long non-polar hydrocarbon tails that do not interact favorably with water.

Question 2

A scientist is comparing the melting points of two fats. Fat A is solid at room temperature, while Fat B is liquid. Which structural feature most likely explains this difference?

Accepted Answer

Fat A is saturated, containing only single bonds, while Fat B is unsaturated, containing double bonds that introduce kinks.

Question 3

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

Accepted Answer

They have both hydrophilic (polar) heads and hydrophobic (non-polar) tails.

Question 4

A red blood cell is placed in a hypotonic solution. What will most likely happen to the cell, and why?

Accepted Answer

Water will enter the cell, causing it to swell and possibly burst, because water moves from high to low solute concentration.

Question 5

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

Accepted Answer

Oxygen ($$O_2)$$

Question 6

Which statement about facilitated diffusion is correct?

Accepted Answer

It requires membrane proteins but does not require energy.

Question 7

A cell uses a sucrose/H$$^+$$ cotransporter to import sucrose. Which of the following best describes this process?

Accepted Answer

Secondary active transport, where H$$^+$$ moves down its gradient and sucrose moves against its gradient.

Question 8

Which of the following changes would most likely increase the fluidity of a cell membrane at room temperature?

Accepted Answer

Increasing the proportion of unsaturated fatty acids in the phospholipids.

Question 9

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

Accepted Answer

It modulates membrane fluidity by preventing tight packing of phospholipids at low temperatures and restricting movement at high temperatures.

Question 10

Which of the following statements about osmosis is correct?

Accepted Answer

Osmosis is the movement of water from areas of high water concentration to areas of low water concentration across a selectively permeable membrane.

Question 11

A mutation causes a membrane protein to lose its ability to change conformation. Which transport process would be most directly affected?

Accepted Answer

Carrier-mediated facilitated diffusion

Question 12

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

Accepted Answer

The kinks caused by double bonds prevent tight packing of phospholipids, creating more space for molecules to pass through.

Question 13

Which of the following is a correct pairing of a membrane protein type and its function?

Accepted Answer

Integral membrane protein – spans the lipid bilayer and often functions as a channel or transporter.

Question 14

A cell is placed in a solution and water exits the cell, causing it to shrink. Which term best describes the solution?

Accepted Answer

Hypertonic

Question 15

Which of the following best describes the direction of net movement for solutes during diffusion?

Accepted Answer

From regions of high concentration to regions of low concentration until equilibrium is reached.

Question 16

Which of the following would most likely decrease the permeability of a biological membrane to glucose?

Accepted Answer

Increasing the proportion of saturated fatty acids in the membrane.

Question 17

Which of the following is NOT a function of membrane proteins?

Accepted Answer

Storing genetic information.

Question 18

A researcher adds a large amount of cholesterol to a cell membrane at high temperature. What is the most likely effect on membrane fluidity?

Accepted Answer

Membrane fluidity will decrease because cholesterol restricts phospholipid movement at high temperatures.

Question 19

Which of the following best describes the process of secondary active transport?

Accepted Answer

It uses the energy stored in an ion gradient to move another substance against its concentration gradient.

Question 20

Which of the following would most likely increase the rate of facilitated diffusion of glucose into a cell?

Accepted Answer

Increasing the number of glucose transport proteins in the membrane.

General Biology Study Notes: Biomolecules, Cell Membranes, and Chemical Bonds

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