An atom of carbon has 6 protons, 6 neutrons and 6

ATI RN

ATI RN Test Bank

An atom of carbon has 6 protons, 6 neutrons and 6 electrons. What is the mass number of this isotope of carbon?

A. 6 B. 9 C. 12 D. 18

Correct Answer: C

Rationale: Mass number = protons + neutrons = 6 + 6 = 12 (carbon-12 isotope).

A chemical substance that helps keep the pH from drastically changing is a(an)

A. acid B. base C. buffer D. isotope

Correct Answer: C

Rationale: Buffers resist pH changes by neutralizing added acids or bases.

What polysaccharide is the storage form of glucose in animals?

A. cellulose B. starch C. sucrose D. glycogen

Correct Answer: D

Rationale: Glycogen is stored in animal liver and muscles as a glucose reserve.

Which of the following is NOT a function of proteins?

A. forming hormones B. forming monosaccharides C. forming transport molecules D. forming hair and nails

Correct Answer: B

Rationale: Proteins don't form monosaccharides (carbohydrates); they serve structural and functional roles.

The rungs of a DNA ladder are made of

A. alternating sugar and phosphate B. complementary base pairs C. alternating uracil and phosphate D. none of the above

Correct Answer: B

Rationale: DNA's rungs are base pairs (A-T, C-G); the backbone is sugar-phosphate.

$89/ 30 days

$150/ 90 days