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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1401. Cell surface markers are
- A. Lipoproteins
- B. Glycolipids
- C. Sphingolipids
- D. Glycoproteins
- E. both b and d
Explanation: The correct answer is both b and d because both glycolipids and glycoproteins are classified as cell surface markers.
Correct answer: both b and d- A. Glycolipids
- B. Glycoproteins
- C. Lipopolysaccharides
- D. Lipoproteins
Explanation: They act as surfactant during respiratory distress syndrome when surfactant production is insufficient or absent, which causes alveolar…
Correct answer: Lipoproteins- A. Within glycerol only
- B. Within fatty acids only
- C. Between fatty acids and glycerol
- D. Within fatty acids and within glycerol
Explanation: The correct answer is 'within fatty acids only.' In unsaturated lipid molecules, carbon-carbon double bonds are present within the fatty…
Correct answer: Within fatty acids only- A. Steroid
- B. Carotenoid
- C. Acylglycerol
- D. Phospholipid
Explanation: The correct answer is acylglycerol. In a condensation reaction, fatty acids react with glycerol to form acylglycerols (such as…
Correct answer: Acylglycerol- A. Chylomicrons
- B. VLDL
- C. LDL
- D. HDL
Explanation: LDL, or low-density lipoprotein, is often referred to as 'bad' cholesterol because it transports cholesterol to the arteries, where it can…
Correct answer: LDL1406. Nitrogenous bases such as choline and serine are a significant part of which of the following?
- A. Sphingolipids
- B. Phospholipids
- C. Phosphodiester
- D. None of these
Explanation: Phospholipids are major components of cell membranes and include nitrogenous bases like choline and serine in their head groups.
Correct answer: Phospholipids- A. A
- B. B
- C. C
- D. D
Explanation: A peptide bond links the carbon atom of one amino acid's carboxyl group to the nitrogen atom of the following amino acid's amino group…
Correct answer: C- A. A
- B. B
- C. C
- D. D
Explanation: The alpha helix is the secondary structure labelled as X, characterized by a right-handed coiled or spiral conformation.
Correct answer: B- A. I.
- B. II.
- C. III.
- D. IV.
Explanation: In an alpha helix, hydrogen bonds form between the carbonyl oxygen (C=O) of one amino acid and the amide hydrogen (N-H) of another amino…
Correct answer: IV.- A. 136
- B. 146
- C. 235
- D. 288
Explanation: hemoglobin molecule is made up of four polypeptide chains, two alpha chains of 141 amino acid residues each and two beta chains of 146…
Correct answer: 146- A. Alanine
- B. Valine
- C. Glycine
- D. Lycine
Explanation: Glycine is the simplest amino acid because it has a hydrogen atom as its side chain. The other amino acids have more complex side chains.
Correct answer: Glycine- A. Alpha carbon & amino group
- B. Amino group & carboxyl group
- C. Carboxyl & R group
- D. R group & alpha carbon
Explanation: The name, amino acid, comes from the amino group and the acid group which are the most reactive parts of the molecule.
Correct answer: Amino group & carboxyl group- A. Hydrogen groups of adjacent amino acids
- B. Non-functional groups of the amino acids
- C. Carboxyl groups and amino groups
- D. Functional groups and hydrogen groups of adjacent amino acids
Explanation: The correct option is: Carboxyl groups and amino groups.Peptide bonds are formed through a condensation reaction between the carboxyl…
Correct answer: Carboxyl groups and amino groups- A. NH3
- B. CO2
- C. H2O
- D. O2
Explanation: Peptide bond formation is a condensation process which involves removal of water molecule
Correct answer: H2O- A. Fatty acids, polysaccharides
- B. Protein, amino acids
- C. Lipids, glucose
- D. None of these options is correct
Explanation: Fatty acids do not catabolize to form polysaccharides. Lipids can be catabolized to fatty acids and glycerol, not glucose.
Correct answer: Protein, amino acids- A. Polyprotein
- B. Polymerase
- C. Polyisomerase
- D. None of these options is correct
Explanation: The correct answer is a) Polyprotein. A long polypeptide that is cut up to generate several small proteins is known as a polyprotein.
Correct answer: Polyprotein- A. Protein
- B. Globular protein
- C. Functional protein
- D. Secretive protein
Explanation: An amino acid joined only by peptide bonds is the straight chain and has the primary structure of a protein.Globular protein has a…
Correct answer: Protein- A. Peripheral protein.
- B. Transmembrane proteins.
- C. Intrinsic proteins.
- D. Intracellular proteins.
Explanation: Peripheral proteins are a group of biologically active molecules formed from amino acids that interact with the surface of the lipid…
Correct answer: Peripheral protein.- A. Three
- B. Six
- C. Nine
- D. Twelve
Explanation: There are nine essential amino acids. They are essential because they cannot be made by the body. They must be taken from food.
Correct answer: Nine- A. A
- B. B
- C. C
- D. D
Explanation: Option A correctly identifies X as amino acid, Y as tRNA and Z as mRNA. X (Amino Acid): The building blocks of proteins.
Correct answer: A