Biology · Chemistry

Biomolecules and Enzymes

1,432 Questions

This topic focuses on biomolecules, specifically proteins, enzymes, and amino acids. It includes questions on enzyme structures, protein folding, and catalysis. These concepts are crucial for medical and biology competitive exams.

Enzyme catalysisProtein structuresAmino acid synthesisPolypeptide chainsBiomolecule properties

Biomolecules and Enzymes Questions

Multiple choice

Which of the following plasma proteins functions by maintaining the colloidal osmotic pressure?

  1. Albumin

  2. Globulin

  3. Fibrinogen

  4. Thrombin

  5. Prothrombin
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Albumin produced only in the liver is the major plasma protein that circulates in the bloodstream. One of the functions of albumin is to maintain intravascular oncotic (colloid osmotic) pressure. To facilitate movement of fluid throughout the body the average capillary pressure is 15 to 25 mm Hg, greater at the arterial end than at the venous end. Serum albumin carries and delivers important nutrients to cells. It binds toxins to avoid toxic effects, binds excessive proteins to act as a buffer and binds hormones and growth peptides to keep them stable.

Multiple choice

Which of the following is the best evidence for the Lock and Key theory of enzyme action?

  1. All isolated enzymes have been identified as proteins.

  2. Compounds similar in structure to substrate a molecule may inhibit the reaction.

  3. Enzymes speed up and determine the direction of a reaction.

  4. Enzymes are found only in cytoplasm of a cell.

  5. Enzymes are found only in the vacuoles of a cell.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

According to Lock and key Theory, the active site of an enzyme is static in nature. It has a specific geometric shape where in the substrate molecule fits. It is just like a key and its particular lock in which levers of key act like active site of the enzyme to open a particular lock (substrate).

Multiple choice

An enzyme is a protein which differs from an inorganic catalyst in that is highly specific. This specificity of the enzyme is associated with the ___________.

  1. insoluble nature of the protein molecule

  2. high molecular weight of the protein molecule

  3. surface configuration of the protein molecule

  4. absence of metallic ions in the protein molecule

  5. soluble nature of the protein molecule
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The specificity of the enzyme is associated with the surface configuration of the protein molecule.

Multiple choice

The monopoly of proteins to form enzymes is now not universal. Certain catalytic RNA (RNA enzymes) like Ribozyme discovered by RNAse- P (Ribonucleases P ) discovered by Altman are not proteins but act as catalysts. These RNA enzymes differ from protein enzymes in _______.

  1. that they catalyse only RNA molecules

  2. that they catalyse only nucleic acid molecules

  3. that they catalyse only phosphoprotein molecules

  4. both 2 and 3

  5. both 1 and 3
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

RNA enzymes only  catalyse only RNA molecules whereas protein enzymes helps to catalyse nucleic acid molecules, phosphoprotein molecules,  etc.

Multiple choice

Why are enzymes, vitamins and hormones classified into a category of biological chemicals?

  1. As they are exclusively synthesized in the body of a living organism

  2. As they help in regulating metabolism

  3. As they enhance oxidative metabolism

  4. As they are conjugated proteins

  5. As they prevent denaturation of proteins
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Enzymes, vitamins and hormones are classified into a category of biological chemicals as they help in regulating the metabolism of the living organism, and maintain the activities of their lives.

Multiple choice

Which of the following statements regarding enzyme inhibition is correct?

  1. Competitive inhibition is seen when a substrate competes with an enzyme for binding to an inhibitor protein.

  2. Non-competitive inhibitors often bind to the enzyme irreversibly.

  3. Non-competitive inhibition of an enzyme can be overcome by adding large amount of substrate.

  4. Competitive inhibition is seen when the substrate and the inhibitor compete for the active site on the enzyme.

  5. Both 3 and 4 are correct.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Competitive inhibition is caused by blocking of active sites of enzyme by an inhibitor that closely resembles with that of the substrate but does not undergo any change.  It is seen when the substrate and the inhibitor compete for the active site on the enzyme.

Multiple choice

Which of the following statements is true regarding enzymes?

  1. Induced fit theory of enzymes was given by Emil Fischer.

  2. Michaelis constant is the substrate concentration at which enzyme reaction proceeds at half the maximum velocity.

  3. Synthesis of enzymes is directed by tRNA.

  4. Enzymes exists in cells as solids.

  5. Zymogen is an enzyme.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Michaelis constant is the substrate concentration at which the reaction velocity is 50% of the Vmax.