1st Year Biology Chapter 3 Notes

• Important Multiple Choice Questions of 1st Year Biology Chapter 3 Notes of First-year Biology.
• Important Fill in the blanks of Chapter Number 3: Enzymes of First-year Biology.
• Important Short Questions of Chapter Number 3: Enzymes of First-year Biology.
• 1. Lock and key model was proposed by: (a) Lorenz Oken (b) Rudolph Virchow (c) Emil Fisher (d) Koshland
• 2. Any factor that can alter the chemistry and shape of an enzyme can effect its rate of: (a) Photolysis (b) Hydrolysis (c) Catalysis (d)  Activity
• 3. The catalytic activity of an enzyme is restricted to its small portion called: (a) Catalytic site (b) Binding site (c) Active site (d) Allosteric site
• 4. Koshland in 1959 proposed the modified form of: (a) Induce Fit model (b) Fluid mosaic model (c) Unit membrane model (d) Lock and key model
• 5. An enzyme and its substrate react with each other through definite charge bearing sites called …… sits. (a) Binding (b) Active (c) Passive (d) Catalytic 
• 6. The active site of the enzyme is made up of two definite regions i.e., the binding site and the: (a) Non-binding site (b) Non-catalytic site (c) Catalytic site (d) Inactive site 
• 7. The non protein part of enzyme responsible for its proper functioning is known as: (a) Product (b) Reactant (c) Cofactor (d) Substarte
• 8. Poisons like cyanide , antibiotics , anti-metabolites and some drugs are examples of: (a) Enzymes (b) Coenzymes (c) Holoenzymes (d) Inhibitors
• 9. An inhibitor is a chemical …… . (a) None of these (b) Substance (c) Protein (d) Enzyme
• 10. An inhibitor react with enzyme but not transformed into … . (a) None of these (b) Co-enzyme (c) Product (d) Enzyme
• 11. The inhibitor which may destroy the globular structure of enzyme is: (a) Reversible (b) Irreversible (c) Non-competitive (d) Competitive
• 12. Irreversible inhibitors form which bond with active site? (a) Ionic bonds (b) Hydrophobic (c) Hydrogen bonds (d) Covalent bonds
• 13 The reversible inhibitors usually constitute: (a) Medium linkage with enzyme (b) Strong linkage with enzyme (c) Wear linkage with enzyme (d) No linkage with enzyme
• What is catalyst? Ans: A substrate which in minute amounts promotes chemical change without itself being used up in the reaction.
• What is co-enzyme? Ans: It is an organic compound which combines with an enzyme and plays an important part in its catalytic reaction, without being consumed in the process. 
• How do irreversible inhibitors check the reaction rate? Ans: The irreversible inhibitors check the reaction rate by occupying the active sites of the enzyme or by destroying their globular structure. 
• What are inhibitors? Ans: An inhibitor is a chemical substance that can react with the enzyme but it is not transformed into products and thus blocks the active site temporarily or permanently.
• Temperature and Enzyme Activity:  The rate of enzyme controlled reaction may increase with increase in temperature but up to certain limit. All enzymes can work at their specific temperature called as optimum temperature. For enzymes of human body 37C is the optimum temperature. Heat provides activation energy and therefore chemical reactions are accelerated at high temperature. Heat also supplies kinetic energy to the reacting molecules, causing them to move rapidly.  Thus the reactants move more quickly and chances of their collision with each other are increased.However, further increase in heat energy also increases the vibrations of atoms which make up the enzyme molecule. If the vibrations become too violent, globular structure essential for enzyme activity is lost and the enzyme is said to be denatured.