All Free Biology MCQs with Answers

• A. Folding
• B. Sequence of amino acids
• C. Coiling
• D. It is due to hydrogen bonding

Explanation: The primary structure of a protein refers to the linear sequence of amino acids that make up the protein chain. It is the most fundamental level of protein structure and is determined by the specific arrangement of amino acids in the polypeptide chain.

• A. Peptide bond is a covalent bond
• B. It is a polyamide
• C. It contain different sequence of amino acids in different proteins
• D. Primary structure is due to hydrogen bonding

Explanation: The primary structure of a protein refers to its linear sequence of amino acids linked by peptide bonds. Hydrogen bonding is not directly involved in forming the primary structure of proteins, as this structure is primarily determined by the sequence of amino acids and the peptide bonds between them. Hence, the statement given in the option'd' is false making it the correct answer.

• A. Primary
• B. Tertiary
• C. Secondary
• D. Quaternary

Explanation: The secondary structure of a protein is a regular coiling or zigzagging of polypeptide chains caused by hydrogen bonding between NH and C = 0 groups of amino acids near each other in the chains. This secondary structure is seen as α-Helix and β-sheets.

• A. Hydrogen bonding
• B. Covalent bond
• C. Debye forces
• D. Dipole-Dipole forces

Explanation: Covalent bond is correct for the primary structure of proteins, as it refers to the bonds formed between the amino acids in the sequence, creating the peptide backbone of the protein.

• A. α-helix
• B. Both A and C
• C. β-sheets
• D. 3-dimensioal folding

Explanation: Alpha helices (A) and beta sheets (C) are types of secondary protein structures. Alpha helices are right-handed coiled structures, while beta sheets consist of beta strands connected laterally by at least two or three backbone hydrogen bonds, forming a pleated sheet. These structures are part of the secondary structure of proteins, which refers to the local folding patterns of the polypeptide backbone.

• A. Result of replication
• B. Result of termination
• C. Result of duplication
• D. Result of translation

Explanation: Translation is the process where the sequence of nucleotides in mRNA is decoded into a sequence of amino acids, ultimately determining the primary structure of a protein. Each set of three nucleotides, called a codon, corresponds to a specific amino acid, allowing the mRNA sequence to be translated into a specific sequence of amino acids. Thus, translation directly influences the primary structure of proteins.

• A. H-Bond
• B. Disulphide linkage
• C. Covalent bond
• D. Amino acids

Explanation: Disulfide linkages are not typically found within α-helices. They form between cysteine residues in proteins, stabilizing tertiary protein structure.

• A. α-Carbon
• B. ẞ-Carbon
• C. Side chain carbon
• D. Carbonyl carbon

Explanation: This carbon atom is part of the carbonyl group (C=O) at the carboxyl end of an amino acid. During peptide bond formation, the carbonyl carbon of one amino acid reacts with the amino group (-NH2) of another amino acid, resulting in the formation of a peptide bond.

• A. Organic polymers
• B. Inorganic polymers
• C. Biopolymers
• D. Synthetic polymers

Explanation: Most biologically important substances are organic compounds (Hiopolymers) built up from skeleton of carbon atoms. Many of them are very large mo1ecq1cand most of these are polymers. The four major classes of organic compounds on living cells are carbohydrates, lipids, proteins and nucleic acids.

• A. Terylene
• B. Nylon 6,6
• C. Protein
• D. Urea

Explanation: Within a protein, multiple amino acids are linked together by peptide bonds, thereby forming a long chain. Peptide bonds are formed by a biochemical reaction that extracts a water molecule as it joins the amino group of one amino acid to the carboxyl group of a neighboring amino acid.