$$\text{Water moves from low solute concentration (high water potential) to high solute concentration (low water potential)}$$

$$\text{Osmolarity} = \sum_{i} c_{i}$$, where $$c_{i} is $$the concentration of each solute

Question 1

Which of the following best explains why saturated fatty acids are solid at room temperature?

Accepted Answer

They have straight chains with no double bonds, allowing molecules to pack closely together.

Question 2

A cell membrane is described by the fluid mosaic model. Which statement best describes this model?

Accepted Answer

The membrane is a flexible phospholipid bilayer with proteins and other molecules embedded throughout.

Question 3

Which property allows phospholipids to spontaneously form bilayers in water?

Accepted Answer

They are amphipathic, with hydrophilic heads and hydrophobic tails.

Question 4

Which of the following is a function of transmembrane proteins in the cell membrane?

Accepted Answer

Transporting substances across the membrane

Question 5

A patient has high levels of LDL and low levels of HDL in their blood. What is the most likely health risk associated with this lipid profile?

Accepted Answer

Increased risk of heart disease due to cholesterol buildup in arteries

Question 6

Which equation correctly represents the movement of water during osmosis across a semipermeable membrane?

Accepted Answer

$$	ext{Water moves from low solute concentration (high water potential) to high solute concentration (low water potential)}$$

Question 7

Which of the following molecules is most likely to cross a cell membrane by simple diffusion?

Accepted Answer

O$$_2$$

Question 8

A cell is placed in a hypertonic solution. What will happen to an animal cell and a plant cell, respectively?

Accepted Answer

Animal cell will shrink (crenate); plant cell will plasmolyze.

Question 9

Which statement best describes secondary active transport?

Accepted Answer

It uses energy stored in an ion gradient created by primary active transport.

Question 10

Which of the following best describes the amphipathic nature of transmembrane proteins?

Accepted Answer

They have hydrophobic regions that interact with lipid tails and hydrophilic regions that interact with aqueous environments.

Question 11

Which of the following is NOT a function of cholesterol in the cell membrane?

Accepted Answer

Catalyzing metabolic reactions

Question 12

Which equation best represents the relationship between osmolarity and solute concentration?

Accepted Answer

$$	ext{Osmolarity} = \sum_{i} c_{i}$$, where $$c_{i} is $$the concentration of each solute

Question 13

Which of the following best describes facilitated diffusion?

Accepted Answer

Passive transport of molecules through a protein channel or carrier

Question 14

A scientist adds a molecule to a cell that blocks all ATP production. Which transport process will be most directly affected?

Accepted Answer

Active transport

Question 15

Which of the following best describes the role of the sodium-potassium pump ($$	ext{Na}^+/	ext{K}^+-$$ATPase) in cells?

Accepted Answer

It uses ATP to pump 3 Na$$^+$$ out and 2 K$$^+ in$$, creating an electrochemical gradient.

Question 16

Which of the following is true about the movement of molecules in simple diffusion?

Accepted Answer

Molecules move from high to low concentration until equilibrium is reached.

Question 17

Which of the following best describes an ester linkage?

Accepted Answer

A covalent bond formed between the hydroxyl group of glycerol and the carboxyl group of a fatty acid during dehydration synthesis.

Question 18

Which of the following is a correct definition of a semipermeable membrane?

Accepted Answer

A membrane that allows some substances (like small or nonpolar molecules) to pass through but restricts others.

Question 19

Which scenario best illustrates the concept of tonicity?

Accepted Answer

A red blood cell placed in pure water swells and bursts due to water entering the cell.

Question 20

Which of the following best describes the difference between symport and antiport in secondary active transport?

Accepted Answer

Symport moves two molecules in the same direction; antiport moves two molecules in opposite directions across a membrane.

Lipids, Membranes, and Transport: General Biology Study Notes

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