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 biology soldiers of defense blood clotting and healing of wounds coagulation of blood blood clotting

Which of the following protein is responsible for spontaneous blood clotting?

  1. Factor XII

  2. Factor XI

  3. Factor IX

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

Factor VIII is an important blood clotting protein, which is also known as anti-haemophilic factor (AHF), encoded by the F$ _{8}$ gene.
Factor VIII circulates in the bloodstream in an inactive form, bound to another molecule, called Von Willebrand factor, until an injury that damages the blood vessels occurs. When injury occurs, the factor VIII is activated and separates from Von Willebrand factor. The active protein interacts with another coagulation factor, called factor IX. This interaction leads to a chain of additional reactions, that form a blood clot.

Multiple choice biology soldiers of defense blood clotting and healing of wounds coagulation of blood blood clotting

Protein required for coagulation of blood is

  1. Haemoglobin

  2. Globulin

  3. Fibrinogen

  4. Albumin
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
The mechanism of blood clotting involves the presence of calcium and other clotting factors, Factor X activates an enzyme called prothrombin activator. The enzyme prothrombin activator then converts plasma protein prothrombin into thrombin. Thrombin is the enzyme which in turn converts fibrinogen into fibrin. Polymerized fibrin together with platelets forms a clot at the wound site. Hence Protein required for coagulation of blood is Fibrinogen. It is a blood plasma protein made in the liver and present in circulating blood.
So, the correct answer is 'Fibrinogen'
Multiple choice biology soldiers of defense blood clotting and healing of wounds coagulation of blood blood clotting

Blood protein which initiates blood coagulation is

  1. Prothrombin

  2. Thrombin

  3. Fibrinogen

  4. Fibrin
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
Prothrombin is a plasma protein essential for blood clotting. Whenever there is an injury, prothrombin activator complex is formed. Prothrombin is converted into thrombin by activators. Thrombin acts as an enzyme and converts plasma protein fibrinogen into fibrin threads which form a clot at the site of injury and bleeding is stopped.
So, the correct answer is 'Prothrombin'.
Multiple choice biology soldiers of defense blood clotting and healing of wounds coagulation of blood blood clotting

Identify the correct sequence of blood coagulation (a) Activation of prothrombin (b) Formation of prothrombin activator (c) Formation of blood clot (d) Conversion of fibrinogen to fibrin

  1. b - d - a - c

  2. b - a - d - c

  3. a - d - c - b

  4. a - b - c - d
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
Blood coagulation occurs in the following sequence:
  • Whenever there is rupture of blood vessels or damage is caused to blood, a complex of substances called prothrombin activator complex is formed. 
  • The activators convert prothrombin into thrombin.
  • Thrombin acts as an enzyme and converts fibrinogen into fibrin threads.
  • Fibrin threads accumulate and clump to form blood clot at the wound site.
So, the correct answer is 'b- a- d- c'.
Multiple choice biology soldiers of defense blood clotting and healing of wounds coagulation of blood blood clotting

Conversion of fibrinogen to fibrin is catalysed by

  1. Thrombin

  2. Prothrombin

  3. Thromboplastin

  4. All of these
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
Thrombin catalyzes the conversion of fibrinogen (factor I)—a soluble plasma protein into long, sticky threads of insoluble fibrin . The fibrin threads form a mesh that traps platelets, blood cells, and plasma.The fibrin mesh work begins to contract in a short period of time and prevents blood loss. 
So, the correct answer is 'Thrombin'
Multiple choice biology soldiers of defense blood clotting and healing of wounds coagulation of blood blood clotting

Which of these are necessary for initiation of blood clotting process?

  1. Prothrombinase and thrombin
  2. Tissue factor hageman factor and $Ca^{2+}$
  3. Prothrobinase and $K^{2+}$
  4. Prothrobinase , tissue factor and $Ca^{2+}$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

There are two processes that can initiate clotting

  1. A very rapid process the so-called extrinsic pathway 
  2. A slower but larger intrinsic pathway
In the extrinsic pathway- Damaged cells display a surface protein called tissue factor
In the intrinsic pathway- Factor 12 (XII) (also called the Hageman factor) circulates in the blood.
Calcium ions are required for the promotion or acceleration of blood clotting pathways
So correct option is B, Tissue factor hageman factor and $Ca^{2+}$.

Multiple choice biology soldiers of defense blood clotting and healing of wounds coagulation of blood blood clotting

Which option is correct for the formation of intrinsic factor-X activator complex for blood coagulation?

  1. Activated Christmas factor + AHG + phospholipid + $Ca^{+2}$
  2. Inactivated Christmas factor + AHG + phospholipid +$Ca^{+2}$
  3. Convertin + AHG + $Ca^{+2}$+ FSF

  4. Phospholipid - protein complex + Proconvertin
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The Hageman factor XII is activated when it comes in contact with a damaged blood vessel. The activated Hageman factor activates the factor XI. The activated factor XI acts on Chrishmas factor IX to form activated IXa. Factor IXa combines with AHG VIII phospholipid and calcium ions to form a complex called intrinsic factor X activator complex. Thus the correct answer is option A.

Multiple choice biology food and it's constituents energy giving food carbohydrate and its test biological molecules

A biological molecule made up of only carbon, hydrogen and oxygen.

  1. Lipids

  2. Proteins

  3. Carbohydrates

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

Carbohydrates (CHO) - These are the principle energy storage molecules. They contain carbon (C), hydrogen (H), and oxygen (0) in a 1:2:1 ratio and are classified according to their size into monosaccharide, disaccharide, polysaccharide.

Monosaccharides are simple sugar having single chain or single ring structure which contains 3-7 carbon atoms. Example is glucose with 6 carbons, 12 hydrogens, and 6 oxygens.

Disaccharides: Double sugars are formed by dehydration reaction between 2 monosaccharides glucose + glucose ------ - > maltose + water. Disaccharides are too large to pass through cell membranes and must be digested to simple sugar units by hydrolysis (add water).

Polysaccharides are long chains of simple sugar molecules. The two major molecules of importance are starch, which is used for storage form for carbohydrate fuel in plants and glycogen, which is used for storage form for carbohydrate fuel in animals.

Function: It is ready source of cellular fuel & cellulose, is used for structural support in plants and carbohydrates help form cell receptors for recognition. Hence, option C is correct.

Multiple choice biology food and it's constituents energy giving food carbohydrate and its test biological molecules

Macro molecule chitin is 

  1. Phosphorus containing polysaccharide

  2. Sulphur containing polysaccharide

  3. Simple polysaccharide

  4. Nitrogen containing polysaccharide
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Macro-molecule chitin is a complex nitrogen-containing polysaccharide containing amino sugars and chemically modified sugar for example -glucosamine, N-acetyl-galactosamine etc.

So, the correct answer is 'Nitrogen containing polysaccharide'

Multiple choice biology food and it's constituents energy giving food carbohydrate and its test biological molecules

The prosthetic group of a conjugated protein classified as a glycoprotein is a

  1. Chromomorphic group

  2. Polysaccharide

  3. Metal ion

  4. Lipid
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
A conjugated protein is a protein that functions in interaction with other (non-polypeptide) chemical groups attached by covalent bonding or weak interactions.  The non-amino part of a conjugated protein is usually called its prosthetic group. Most prosthetic groups are formed from vitamins. Glycoproteins are proteins that contain various amounts of carbohydrate. A number of very important proteins fall in this class, including many of the blood plasma proteins and a large number of en­zymes and hormones. The carbohydrate bonded at each site of the protein may consist of a sin­gle monosaccharide unit or a linear or branched chain of several mono saccharides (called an oligosaccharide).

So, the correct answer is 'Polysaccharide'.
Multiple choice biology digestive system of human assimilation of food and egestion assimilation of food components and importance of food

Which of the following is known as the building block of proteins?

  1. Amino acids

  2. Enzymes

  3. Fatty acids

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

Amino acids are directly absorbed into blood stream. Blood carries these amino acids to the tissues where they become part of the metabolic pool, from which body proteins are synthesized. Hence, it is known as the building block of proteins.