Free Biological Molecules MCQs with Answers
1,790 Biological Molecules MCQs from Biology, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
The chapter covers water's polarity and biological roles, carbohydrates, lipids, proteins and nucleic acids, including their monomers, bonds, structures and functions. It also distinguishes RNA from DNA and explains conjugated molecules such as glycoproteins, glycolipids and nucleoproteins, which combine organic molecules with a non-protein component.
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661. Collagen is a:
- A. Fibrous protein
- B. Globular protein
- C. Lipid
- D. Carbohydrate
Explanation: Collagen is an insoluble fibrous protein found extensively in the connective tissue of skin, tendons and bone.
Correct answer: Fibrous protein- A. The human body does not produce Enzymes
- B. The human body does not produce Vitamins
- C. Proteins are energy source for our body
- D. Nucleic acids are building blocks for our body
Explanation: Vitamins are organic compounds which have to be obtained from the diet, either because an organism does not have the enzymes necessary to…
Correct answer: The human body does not produce Vitamins- A. They are highly hydrated and therefore can store lots of energy
- B. They always have short fatty acid chains for easy access by metabolic enzymes
- C. The carbon atoms of the fatty acid chains are highly reduced and therefore yield more energy upon oxidation
- D. Polysaccharides, which would actually be a better energy storage form, would dissolve in the body
Explanation: The correct answer is C: The carbon atoms of the fatty acid chains are highly reduced and therefore yield more energy upon oxidation.
Correct answer: The carbon atoms of the fatty acid chains are highly reduced and therefore yield more energy upon oxidation- A. They contain double bonds between carbon atoms
- B. They have a higher melting point compared to unsaturated fatty acids
- C. They are commonly found in plant oils
- D. They contribute to increased levels of 'good' cholesterol (HDL) in the body
Explanation: Saturated fatty acids have a higher melting point compared to unsaturated fatty acids.
Correct answer: They have a higher melting point compared to unsaturated fatty acids- A. All known α-amino acids possess an asymmetric carbon atom except glycine
- B. Certain antibiotics contain some amino acids in L-isomer form
- C. If an amino acid has more than one asymmetric carbon atom, all the isomers shall be optically active
- D. None of the above
Explanation: Statement C is incorrect.If an amino acid has multiple asymmetric carbon atoms , not all isomers will necessarily be optically active.
Correct answer: If an amino acid has more than one asymmetric carbon atom, all the isomers shall be optically active- A. Anabolic Process
- B. Catabolic Process
- C. Both anabolic and catabolic
- D. None of the above
Explanation: The formation of phosphodiester bonds between two nucleotides is an anabolic process.
Correct answer: Anabolic Process- A. I and IV
- B. I and III
- C. II and IV
- D. II and III
Explanation: The DNA strands are antiparallel i.e. run in opposite directions. Synthesis of new daughter strand by DNA polymerase is only in the 5' to…
Correct answer: I and III- A. 20
- B. 51
- C. 102
- D. 153
Explanation: Each amino acid is coded by a codon of 3 nucleotides bases. Hence, the least number of base pairs 20 x 3 + 31 × 3 = 153.
Correct answer: 153- A. Coiled around a common axis
- B. Coiled around each other
- C. Coiled differently
- D. Coiled over protein sheath
Explanation: According to the Watson-Crick model, the DNA molecule consists of two long, parallel chains which are joined together by short crossbars…
Correct answer: Coiled around a common axis- A. D-glucosamine
- B. lipo glycans
- C. N - acetyl glucosamine
- D. Keratin sulphate and chondroitin sulphate
Explanation: This is the correct answer. The chitinous exoskeleton of arthropods is formed by the polymerization of N-acetylglucosamine, a derivative…
Correct answer: N - acetyl glucosamine- A. Molecular Biology
- B. Microbiology
- C. Biotechnology
- D. Genetics
Explanation: Molecular biology is the branch of biology that deals with the molecular basis of biological activity.
Correct answer: Molecular Biology- A. All the valencies of carbon are satisfied by single bonds
- B. They contain even number of carbon atoms
- C. Their structure has bends which makes them more fluid
- D. Their structure is chain-like which allows them to be more fluid
Explanation: This statement is the correct explanation for why fats containing unsaturated fatty acids are liquid at room temperature.
Correct answer: Their structure has bends which makes them more fluid- A. Label C is a glycosidic linkage
- B. Compound A loses OH- ions
- C. Compounds labeled B has Carboxylic functional group
- D. Dehydration synthesis of A and B forms wax
Explanation: B represents fatty acids, which contain the carboxylic acid group (-COOH).
Correct answer: Compounds labeled B has Carboxylic functional group- A. Disrupts the primary or secondary or tertiary structure of protein
- B. Disrupts the secondary and tertiary structures only
- C. Disrupts all the primary, secondary and tertiary and even the quaternary structure of protein
- D. Will not affect the original biological activity
Explanation: Denaturation can disrupt the secondary and tertiary structures of a protein.
Correct answer: Disrupts the secondary and tertiary structures only675. Proteins are;
- A. Homopolymer
- B. Heteropolymer
- C. Homogenous mixture of amino acids
- D. Heterogeneous mixture of amino acids
Explanation: Proteins are considered heteropolymers. A heteropolymer refers to a polymer composed of different types of monomers.
Correct answer: Heteropolymer- A. Hydrogen bonds only
- B. Hydrogen bonds and ionic bonds only
- C. Hydrogen bonds , ionic bonds and hydrophobic interactions
- D. Hydrogen bonds, ionic bonds and disulphide bonds
Explanation: In addition to hydrogen bonds and ionic bonds, disulfide bonds are another important type of bond involved in maintaining the tertiary…
Correct answer: Hydrogen bonds, ionic bonds and disulphide bonds- A. Quaternary, Quaternary
- B. Quaternary, Tertiary
- C. Tertiary, Secondary
- D. Secondary, Quaternary
Explanation: Haemoglobin has a quaternary structure because it is composed of four protein chains (two alpha chains and two beta chains) that interact…
Correct answer: Quaternary, Tertiary- A. A
- B. B
- C. C
- D. D
Explanation: The nucleotide is most energetic at point D because it is in the form of ATP, which contains three phosphate groups.
Correct answer: D679. If a DNA has a total of 50 nucleotides with 15 adenines. How many sets of triple bonds are present?
- A. 15
- B. 10
- C. 30
- D. 20
Explanation: In DNA, the base pairing between adenine (A) and thymine (T) is established by two hydrogen bonds, while the base pairing between cytosine…
Correct answer: 10- A. Cellulose units
- B. Hexose units
- C. Pentose units
- D. Sucrose units
Explanation: The correct answer is hexose units. Most polysaccharides are comprised of hexose units like glucose, which is a six-carbon sugar.
Correct answer: Hexose units