Question 1

Which of the following statements best explains why DNA is more stable than RNA under cellular conditions?

Accepted Answer

DNA contains deoxyribose, which lacks a hydroxyl group at the 2' carbon, making it less susceptible to hydrolysis.

Question 2

A scientist discovers a nucleic acid molecule with the following characteristics: it contains ribose sugar, uracil as a nitrogenous base, and is usually single-stranded. What type of molecule is this?

Accepted Answer

RNA

Question 3

Which of the following best describes the directionality of a nucleic acid strand?

Accepted Answer

It has a 5' phosphate group at one end and a 3' hydroxyl group at the other.

Question 4

During DNA replication, which base pairs with cytosine, and how many hydrogen bonds are formed between them?

Accepted Answer

Guanine; 3 hydrogen bonds

Question 5

Which of the following is a correct statement about the structure of a phospholipid in a biological membrane?

Accepted Answer

It has a hydrophilic head and two hydrophobic fatty acid tails.

Question 6

A red blood cell is placed in a solution and begins to swell and burst. Which of the following best explains what happened?

Accepted Answer

The solution is hypotonic relative to the cell, causing water to enter by osmosis.

Question 7

Which of the following best describes the function of the rough endoplasmic reticulum (RER)?

Accepted Answer

Synthesis of proteins for secretion or insertion into membranes

Question 8

A muscle cell that relies heavily on aerobic metabolism is likely to have which of the following features?

Accepted Answer

A high number of mitochondria

Question 9

Which of the following is evidence supporting the endosymbiotic theory for the origin of mitochondria?

Accepted Answer

Mitochondria have their own circular DNA and ribosomes similar to bacteria.

Question 10

Which of the following best explains why cells are generally small in size?

Accepted Answer

A small cell has a higher surface area-to-volume ratio, facilitating efficient exchange of materials.

Question 11

A patient with a genetic defect in lysosomal enzymes is likely to experience which of the following cellular problems?

Accepted Answer

Accumulation of undigested macromolecules within the cell

Question 12

Which of the following best describes the role of integral membrane proteins in the plasma membrane?

Accepted Answer

They span the membrane and can function as channels or transporters for specific molecules.

Question 13

Which of the following scenarios best illustrates facilitated diffusion?

Accepted Answer

Glucose entering a cell through a specific transport protein down its concentration gradient

Question 14

Which of the following is a function of the Golgi apparatus in eukaryotic cells?

Accepted Answer

Modifying, sorting, and packaging proteins for secretion or delivery to other organelles

Question 15

A cell is observed to have a large number of smooth endoplasmic reticulum. Which of the following is the most likely function of this cell?

Accepted Answer

Synthesis of lipids and detoxification of drugs

Question 16

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

Accepted Answer

Their hydrophilic heads interact with water while their hydrophobic tails avoid water, resulting in a bilayer.

Question 17

Which of the following best describes the function of the cytoskeleton in eukaryotic cells?

Accepted Answer

It provides structural support, maintains cell shape, and enables movement of organelles.

Question 18

A mutation causes a cell to lack functional motor proteins. Which of the following cellular processes would be most directly affected?

Accepted Answer

Movement of vesicles along microtubules

Question 19

Which of the following best explains why integral membrane proteins can function as channels for polar molecules?

Accepted Answer

They have hydrophilic interiors that allow polar molecules to pass through the hydrophobic membrane.

Question 20

Which of the following equations correctly represents the relationship between surface area and volume for a spherical cell, and why is this relationship important?

Accepted Answer

$$	ext{Surface Area} = 4\pi r^2$, $$	ext{Volume} = \frac{4}{3}\pi $$r^3$$; as a cell increases in size, its volume increases faster than its surface area, limiting efficient exchange of materials.$

Nucleic Acids: Structure, Function, and Types

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