9th Biology Chapter # 6 All Punjab Board Papers | 5 Years Old Board Papers Short questions | Repeated short questions in all Board Papers

   CHAPTER No. 6

1.                  Define metabolism.                                                

Ans:    It is a set of biochemical reactions that occur in living organisms in order to maintain life.

2.                  Define anabolism. Is respiration catabolism? Give example.

Ans:    Anabolism: The biochemical reaction in which larger molecules are synthesized is called anabolism.

            Yes, respiration is catabolism because in respiration larger molecules are broken down and energy is released.

3.                  Define biocatalysts./ Write two benefits of biocatalysts.         

Ans:    Biocatalysts are enzymes which speed up and regulate metabolic pathways.

4.                  Define substrate and product./ What is substrate?/ Define the product of an enzyme action.

Ans:    The molecules at which enzymes act are called substrates and enzymes converts substrate into different molecules called products.

5.                  Define activation energy. How Enzymes effect on it?      

Ans:    Minimum energy required to start the reaction.

6.                  How do Enzymes lower the activation energy?                         

Ans:    Enzymes may alter the shape of substrate and reduce the requirement of energy for this change. Some enzymes do so by disrupting the charge distribution on substrate.

7.                  Write any two characteristics of enzyme.

Ans:    1- Almost all enzymes are protein i.e. they are made of amino acids.

            2- Enzymes are usually very specific for the type of reaction and for the nature of their substrates

8.                  Who first used the term enzyme?

Ans:    Winhelm Kuhne was first used the term enzymes.

9.                  Define co-factors. Write an example.

Ans:    If the enzymes require non-proteins molecules or ions called cofactors.

            Example:   Metal ions, flavin and heme.

10.    What are cofactors of an enzyme? Differentiate between prosthetic group and co-enzyme                       

Ans:    Some Enzyme need additional component to work these none-protein molecules or ions called co-factors.

            If organic cofactor is tightly bound to enzyme they are called prosthetic group. If organic cofactor are loosely bound to enzyme are called co-enzyme.

11.              Define prosthetic group and co-enzyme./ Define Prosthetic Group.

Ans:    Prosthetic Group:  If organic co-factor are tightly bound to enzymes, they are called prosthetic groups co-enzyme: If organic cofactors are loosely attached with enzyme. They are called co-enzyme

12.              Define cofactor and coenzyme./ Write difference between cofactors and coenzymes.     

Ans:    Cofactor: Some enzymes requires non-protein molecules or ions called cofactors.

Coenzyme: If organic cofactors are loosely attached with enzyme, they are called coenzyme.

13.              Define active site of an enzyme.

Ans:    A small portion of enzyme molecule is directly involved in catalysis. This catalytic region is called active site.

14.              Write names of two co-enzyme.   Or        Name three important vitamins which act as co-enzyme.                                               

Ans:    1- Riboflavin              2- Thiamine                3- Folic acid

15.              What is meant by metabolic pathway?

Ans:    Several enzymes can work together in specific order, creating metabolic pathways. In a metabolic pathway, one enzyme takes the product of another enzyme as a substrate. After the reaction, the product is passed on to the next enzyme.

16.              What is meant by enzymes? Also write any one function of it.

Ans:    Enzymes are the proteins that catalyze i.e. 1.speed up biochemical reactions and are cannot changed itself during reaction. Function:

1-                 Enzymes lower the energy of the activation in several ways.

ii- They may alter the shape of substrate and reduce the requirement of energy for this change.

17.              Describe the use of enzymes in brewing industry./ Write the uses of enzymes in food and beverage industry.                                                                          

Ans:    Enzyme breaks starch and proteins. The products are used by yeast for fermentation to produce alcohol.

18.              What do you know about brewing industry?                  

Ans:    Enzymes break starch and proteins. The products are used by yeast for fermentation (to produce alcohol).

19.              Name those industries where enzymes are used./ What factors affect the rate of enzyme reaction?                                                       

Ans:    1- Food industry                   2- Brewing industry

            3- Paper industry                  4- Biological detergent

20.              Give two uses of biological detergents.                  

Ans:    Protease:   It is used for removal of protein stains from clothes.

            Amylase:  It is used in dish washing to remove resistant starch residues.

21.              What is biological detergent? Give an example also.

Ans:    These are the particles which are used to remove dirt particles from the substances.

            Example:  protease, amylas, enzyme.

22.              Write down two uses of enzymes.           

Ans:    Enzymes break starch into simple sugars are used in the production of white bread, bun etc. Enzymes break starch to lower its viscosity that aids in making the paper.

23.              What is meant by denaturation of enzyme?

Ans:    When temperature is raised well above the optimum temperature, heat energy increases the vibrations of atoms of enzyme and the globular structure of enzyme is lost. This is known as the denaturation of enzyme.

24.              What is the effect of temperature on enzymes?

Ans:    Increase in temperature speeds up the rate of enzyme catalyzed reactions, but only to a point. Every enzyme works at its maximum rate at a specific temperature called as the optimum temperature for that enzyme.

25.              How does pH affect enzyme activity?

Ans:    A slight change in pH causes retardation in enzyme activity or blocks it completely. Every enzyme has its specific pH value.

            Change in pH can affect the ionization of the amino acids at the active site. These are point that effects the pH enzymes activities.

26.              Define Optimum temperature. What is the Optimum temperature of human enzymes?                                                 

Ans:    It is the temperature at which every enzyme works at its maximum rate at specific temperature. Example:The optimum temperature for human enzyme is 37^oC.

27.              What is effect on speed of enzymes by increasing temperature?

Ans:    Increase in temperature speeds up the rate of enzymes catalyzed reaction, but only to a point. Every enzyme work at its maximum rate at a specific temperature called optimum temperature.

28.              What is the effect of substrate concentration on the speed of enzymes?

Ans:    If enzymes molecules are available in a reaction increase in the substrate concentration increases the rate of reaction. If enzyme molecules are not available then increase the substrate concentration decreases the rate of reaction.

29.              What is meant by saturation of active site?

Ans:    When the active sites of all enzymes are occupied at high substrate concentration. Any more substrate molecules do not find free sites active sites. This state is called saturation of active sites and reaction rate does not increase.

30.      Write and explain the equation for the mechanism of enzyme action

Ans:    (complex)                 

            When enzyme attaches with substrate, a temporary enzyme-substrate complex is formed. Enzyme catalyzes the reaction and substrate is transformed into product.

31.             Define Lock and Key Model.                                              

Ans:    “Lock” and key model” According to this model, both enzymes and substrate specific shape that fit exactly into one another. This model explains enzyme specificity.

32.              What is induced Fit Model of enzyme action? Or Give Koshland model regarding mechanism of enzyme action.                    

Ans:    According to this model, active site is not a rigid structure rather it is molded into required shape to perform its function. “Induced-fit model” is more acceptable than “lock and key model” of enzyme action.

33.              Difference b/w intracellular and extracellular enzymes.

Ans:    Intracellular enzymes are enzymes of glycolysis. Extracellular enzymes are pepsin.

34.              Write down the names of enzymes that act on protein and starch.   

Ans:    Protein is broken by protease enzyme.

            Starch is broken by amylase enzyme.

35.              What is the function of Amylase and Lipase?

Ans:    The enzymes protease (which breaks peptide bonds in protein) will not work on starch (which is broken down as amylase). Similarly lipase enzymes acts only on lipids and digests them into fatty acids and glycerol.

36.             Write down the specificity of enzymes.                          

Ans:    There are over 2000 known enzymes, each of which is involved in one specific chemical reaction. Enzymes are also substrate specific. The enzyme protease will not work on starch.

37.              Write name of two enzymes:/ Difference b/w protease and amylase enzymes.    

Ans:    1- Protease (which break the peptide bond in proteins)

            2- Amylase (which breaks the starch)