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Quiz Chapter 4: Chemical Composition in Cells

10 questions · Form 4 Biology Bab 4: Chemical Composition in Cells

Question 1 of 10Score: 0

Which component of a nucleotide differs between a DNA strand and an RNA strand?

Full Question List & Answer Key

Prefer reading to quizzing? All 10 questions are listed below with the answer and explanation under each one.

1. Which component of a nucleotide differs between a DNA strand and an RNA strand?

  1. A. Phosphate group
  2. B. Pentose sugar and nitrogenous bases
  3. C. Ester bond type
  4. D. Carboxyl group
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Answer: B

DNA contains deoxyribose sugar and Thymine, whereas RNA contains ribose sugar and Uracil.

2. Why does water have a high specific heat capacity (4.2 kJ kg-1 °C-1?

  1. A. Oxygen and hydrogen atoms share electrons equally.
  2. B. Energy is required to break numerous hydrogen bonds before temperature rises.
  3. C. Water molecules are linked by strong covalent ester bonds.
  4. D. Water contains heavy mineral salts.
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Answer: B

A large amount of thermal energy is absorbed to break hydrogen bonds between water molecules before kinetic energy and temperature increase.

3. In a DNA molecule, if 30% of the nitrogenous bases are Guanine (G), what percentage of the bases will be Thymine (T)?

  1. A. 30%
  2. B. 20%
  3. C. 40%
  4. D. 60%
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Answer: B

According to Chargaff's rules, G = C (30% + 30% = 60%). The remaining 40% is split equally between A and T (40% / 2 = 20% Thymine).

4. Which of the following disaccharides is classified as a NON-REDUCING sugar?

  1. A. Maltose
  2. B. Sucrose
  3. C. Lactose
  4. D. Cellobiose
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Answer: B

Sucrose is the only common disaccharide that does not reduce Benedict's solution because its reducing aldehyde and ketone groups are involved in the glycosidic bond.

5. Why is cellulose impossible for humans to digest, yet essential in the human diet?

  1. A. Humans lack the cellulase enzyme; cellulose acts as dietary fiber to prevent constipation.
  2. B. Cellulose poisons digestive enzymes.
  3. C. Cellulose dissolves instantly in stomach acid without absorption.
  4. D. Cellulose is absorbed directly without digestion.
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Answer: A

Humans do not produce cellulase to digest beta-glycosidic bonds in cellulose, but it provides essential dietary roughage to stimulate peristalsis.

6. What nitrogenous base is present exclusively in RNA and replaces Thymine found in DNA?

  1. A. Adenine
  2. B. Guanine
  3. C. Cytosine
  4. D. Uracil
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Answer: D

Uracil (U) is a pyrimidine nitrogenous base unique to RNA, pairing with Adenine in place of Thymine.

7. Hemoglobin consists of four interconnected polypeptide subunits. What structural level of protein organization does this represent?

  1. A. Primary structure
  2. B. Secondary structure
  3. C. Tertiary structure
  4. D. Quaternary structure
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Answer: D

Quaternary structure describes proteins containing two or more polypeptide chains joined into a single functional unit.

8. The condensation of one glycerol molecule with three fatty acid molecules produces a triglyceride and how many water molecules?

  1. A. 1
  2. B. 2
  3. C. 3
  4. D. 4
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Answer: C

Forming three ester bonds between glycerol and three fatty acid chains releases 3 molecules of water in a condensation reaction.

9. Which of the following organic compounds is composed of carbon, hydrogen, oxygen, nitrogen, and sulfur?

  1. A. Carbohydrate
  2. B. Lipid
  3. C. Protein
  4. D. Nucleic acid
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Answer: C

Proteins contain amino acids, some of which (like cysteine and methionine) possess sulfur atoms.

10. What forms the structural backbone of a single polynucleotide strand in DNA?

  1. A. Alternating hydrogen and peptide bonds
  2. B. Complementary nitrogenous base pairs
  3. C. Alternating phosphate groups and pentose sugars linked by phosphodiester bonds
  4. D. Fatty acid chains bound to glycerol
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Answer: C

The DNA strand backbone consists of repeating sugar-phosphate units linked covalently via phosphodiester bonds.

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