All Free Biology MCQs with Answers

4421. Each alpha chain of hemoglobin consists of:

• A. 151 amino acids
• B. 146 amino acids
• C. 141 amino acids
• D. 156 amino acids

Explanation: Each alpha chain of hemoglobin consists of 141 amino acids.

4422. Each beta chain of hemoglobin consists of:

• A. 146 amino acids
• B. 156 amino acids
• C. 141 amino acids
• D. 151 amino acids

Explanation: Each beta chain of hemoglobin consists of 146 amino acids.

4423. Number of peptides bond involved in stabilization of primary structure of a molecule of hemoglobin is:

• A. 574
• B. 570
• C. 572
• D. 573

Explanation: 574 as 141×2= 282 and 146×2= 292 then 282+292-574

4424. Number of peptide bonds involved in maintenance of primary structure of shorter chain of insulin is:

• A. 30
• B. 21
• C. 20
• D. 19

Explanation: Shorter chain of insulin consists of 21 amino acids, thus having 20 peptide bonds.

4425. The size of a protein molecule at primary level is determined by:

• A. Number of amino acids
• B. Type of amino acids
• C. Number and type of amino acids
• D. Number and sequence of amino acids

Explanation: The primary structure of protein is determined by number and sequence of amino acids. For example, primary structure of insulin consists of 51 amino acids that are arranged in two chains in a specific sequence.

4426. Due to unique and specific arrangement of same amino acids more than _ different proteins are found in human body.

• A. 10,000
• B. 1000
• C. 10,0000
• D. 100

Explanation: In human body all the proteins are synthesized from same twenty amino acids however their diversity depends upon number and sequence of amino acids in each protein. More then 10,000 types of proteins have been discovered from human bodies so far.

4427. If one amino acid out of 574 amino acids is replaced by another in a hemoglobin molecule it will lose following properties, EXCEPT:

• A. Shape
• B. Functional capacity
• C. Oxygen carrying capacity
• D. Quaternary level

Explanation: By changing sequence of amino acids in a quaternary protein the structure and function of proteins is changed but it will remain a new protein of quaternary level. If one amino acid out of 574 amino acids is replaced by another in a hemoglobin molecule, it will lose its quaternary level.The quaternary level of a protein refers to the association of multiple protein subunits to form a multimeric protein. Hemoglobin is a quaternary protein, meaning that it is made up of four subunits. The quaternary structure of hemoglobin is important for its ability to bind oxygen.

4428. Hypoxia which may lead to death is the ultimate consequence of a change occurred initially at _ level of hemoglobin structure.

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

Explanation: Any change in hemoglobin at primary level changes the overall configuration of hemoglobin and as a result it stops functioning properly.

4429. It is a very uniform geometric structure with 3.6 amino acids in each turn of the helix:

• A. α-helix
• B. β-helix
• C. α-pleated sheet
• D. β-pleated sheet

Explanation: Alpha helix is also called a classic Pauling-Corey-Branson α-helix. The 3.613 is also used for this type of helix denoting the average number of residues per helical turn, with 13 atoms being involved in the ring formed by the hydrogen bond.

4430. The helical structure of secondary protein is kept by the formation of _ among amino acid molecules in successive turns of the spiral:

• A. Ionic bond
• B. Peptide bond
• C. Hydrogen bond
• D. Disulphide bond

Explanation: The coils and folds of secondary structure are stabilized by hydrogen bonds between consecutive folds or turns /coils.