Biology · Chemistry

Biomolecules and Enzymes

1,501 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 cytochromes is a highly soluble protein?

  1. cytochrome a

  2. cytochrome b

  3. cytochrome c

  4. cytochrome d
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

 Cytochrome c is a highly soluble protein.The heme group of cytochrome c accepts electrons from the bc1 complex and transfers electrons to the complex IV. Cytochrome c is also involved in initiation of apoptosis.

Multiple choice

GCG stands for which of the following amino acids?

  1. Glutamine

  2. Alanine

  3. Serine

  4. Proline
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The codon GCG (Glycine-Cytosine-Guanine) codes for the amino acid Alanine. This is a standard codon in the genetic code. Glutamine is coded by CAA/CAG, Serine by multiple codons including UCU/UCC/UCA/UCG/AGU/AGC, and Proline by CCU/CCC/CCA/CCG.

Multiple choice

Transamination is

  1. conversion of urea into ammonia

  2. conversion of ammonia into urea

  3. removal of amino group

  4. removal of protein
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Transamination is the process where an amino group is transferred from an amino acid to a keto acid, forming a new amino acid. This is a key step in amino acid metabolism where nitrogen is ultimately converted to urea in the liver. Option B correctly identifies conversion of ammonia to urea (urea cycle), while C describes deamination (removal, not transfer). Option A is the reverse of what actually happens.

Multiple choice

Enzymes are

  1. proteins

  2. pigments

  3. catalysts

  4. organic molecules
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Enzymes are biological catalysts that speed up chemical reactions without being consumed. While most enzymes are proteins (option A), they are fundamentally defined by their catalytic function, not their chemical composition.

Multiple choice

_________ act as basic amino acids.

  1. Glutamic acid and arginine

  2. Glycine and serine

  3. Aspartic acid and glutamic acid

  4. Lysine and argenine

  5. Both (1) and (2)
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

This option is correct.

Multiple choice

Which amongst the following pairs is incorrect?

  1. Acetic acid : Vinegar

  2. Amino acid : Proteins

  3. Tonic acid : Leather

  4. None of these
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Option C states 'Tonic acid: Leather' which is incorrect. The correct pairing should be 'Tannic acid: Leather' because tannic acid (or tannins) are used in leather tanning to preserve and soften animal hides. 'Tonic acid' appears to be a typo or error - there is no such compound used in leather processing. Options A and B (Acetic acid: Vinegar, Amino acid: Proteins) are correct pairings.

Multiple choice

Consider the following statements: Keratin is

  1. a protein.
  2. a hormone.
  3. present in hair.
  4. present in nails. Which of these statements are correct?

  1. 1 and 2

  2. 1 and 4

  3. 2 and 3

  4. 1, 3 and 4
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Keratin is a fibrous structural protein that is the key structural material for making up hair, nails, horns, feathers, and the outer layer of human skin. It is not a hormone - hormones are chemical signaling molecules. Keratin provides mechanical protection and is responsible for the strength and toughness of these structures.

Multiple choice

Which of the following statements about enzyme DD-transpeptidase is true?

  1. It provides antigenicity to the cell wall.

  2. It makes the cell wall semi-permeable.

  3. It makes the cell wall strong and rigid.

  4. It breaks the amino acid linkages in the cell wall.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

DD-transpeptidase helps in cross linking between amino acids in different linear sugar amino chains. It results in a 3-dimensional structure that is strong and rigid.

Multiple choice

The most abundant protein found on Earth is

  1. PEP caroxylase

  2. RUBISCO

  3. Aldolase

  4. Transketolase
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

RUBISCO (Ribulose-1,5-bisphosphate carboxylase/oxygenase) is Earths most abundant protein. It catalyzes carbon fixation in photosynthetic organisms plants, algae, cyanobacteria comprising up to 50% of leaf soluble protein.

Multiple choice

The three-dimensional shape of protein is maintained by

  1. hydrogen bonds

  2. peptide bonds

  3. ionic bonds

  4. None of these
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Each protein has a specific three-dimensional structure that is maintained by hydrogen bonds. Normal protein functions require the maintenance of this structure.