Biology ยท 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 is not an example of simple protein?

  1. Albumin

  2. Globulin

  3. Glutelin

  4. Casein
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Casein is a phosphoprotein, not a simple protein. Simple proteins (albumins, globulins, glutelins) yield only amino acids on hydrolysis. Casein contains phosphate groups, making it a conjugated protein. This distinction is based on chemical composition after hydrolysis.

Multiple choice

Which of the following is not protein?

  1. Enzyme

  2. Apoenzyme

  3. Coenzyme

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

Coenzymes are small organic non-protein molecules that assist enzymes in catalyzing reactions. Enzymes, apoenzymes (protein part of enzyme), and isoenzymes (different forms of the same enzyme) are all proteins. Only coenzymes are not proteins.

Multiple choice

The proteins, which are different in peptide sequence but have a similar structure in the process of evolution are said to be

  1. convergent

  2. divergent

  3. opportunistic

  4. incidental
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Proteins that are different in peptide sequence but have similar structure through evolution are termed convergent. This describes convergent evolution where unrelated proteins independently evolve similar structural features to perform similar functions. Divergent evolution refers to homologous proteins that have evolved from a common ancestor and share sequence similarity.

Multiple choice

Proteins which are different in peptide sequence but have a similar structure in the process of evolution are said to be:

  1. Convergent

  2. Divergent

  3. Opportunistic

  4. Incidental
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Proteins that have different amino acid sequences (primary structure) but similar three-dimensional structures and often similar functions due to evolutionary pressures are said to show convergent evolution at the structural level. This is different from divergent evolution where homologous proteins evolve from a common ancestor.

Multiple choice

_____ are globular proteins.

  1. Beta globulin and fibrin

  2. Collagen and titin

  3. Elastin and beta globulin

  4. Beta globulin and titin

  5. Collagen and elastin
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Beta globulin and fibrin are globular proteins.

Multiple choice

A set of globular proteins is

  1. Albumin, haemoglobin, thrombin

  2. Haemoglobin, myoglobin, elastin

  3. Keratin, elastin, myoglobin

  4. Thrombin, keratin, haemoglobin

  5. Keratin, haemoglobin, elastin
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

All are globular proteins.

Multiple choice

A Spanish research team found that a natural enzyme ____ in the human body can prevent the body cells from ageing.

  1. telomerase

  2. ptyalin

  3. co-enzyme 23

  4. interferon 90
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Telomerase is an enzyme that maintains telomeres (protective caps at the ends of chromosomes), which are associated with cellular aging. Spanish researchers discovered this enzyme's role in preventing cellular aging by maintaining telomere length. Ptyalin is a digestive enzyme, co-enzyme 23 is not a standard enzyme, and interferon 90 relates to immune response rather than aging.

Multiple choice

Silk contains a protein known as

  1. fibrin

  2. casein

  3. fibroin

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

Silk fibers are primarily composed of fibroin, a fibrous protein produced by silkworms. Fibrin is involved in blood clotting, casein is milk protein, making fibroin the correct silk protein.

Multiple choice

Which of the following is an iron storing protein?

  1. Alpha glubulin

  2. Gamma glubulin

  3. Ferritin

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

Ferritin is the primary iron-storing protein in animals, plants, and bacteria. It stores iron in a soluble, non-toxic form. Alpha globulins and gamma globulins are blood proteins involved in other functions (like transport and immunity). Albumins are transport proteins.

Multiple choice

Protein structure is the biomolecular structure of a protein molecule. Which of the following statments regarding the tertiary structure of proteins is incorrect?

  1. Hydrophobic interactions also contribute to the tertiary structure.

  2. Hydrogen bonds are also present in the tertiary structure of proteins.

  3. Electrostatic interactions are present between charged amino acid chains.

  4. The folding of the polypeptide chain is stabilised by strong, non-covalent interactions.

  5. The linear sequence of polypeptide chain is folded into compact globular structure.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The folding of the polypeptide chain is stabilised by weak, non-covalent interactions.

Multiple choice

Casein and collagen are examples of

  1. scleroproteins

  2. globulins

  3. albumins

  4. metalloproteins

  5. protamines
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

These proteins are linked with various metals. Examples: casein, collagen, ceruloplasmin, etc.