Biology

1. 1 S.S.A ( Siddique Science Academy)
10/C officers Colony Bahawalnagar ( Contect# 03338810387, 03000831969)
Prepared by;Miss ANZAL FAIQA YOUSUF (M.S.c BOTANY I.U.B)
BIOLOGY 9Th
Unit -6 ENZYMES
1. What is true about enzymes?
{A} they make biochemical reactions to proceed spontaneously
{b} Theylower the activation energyof a reaction
{c} They are not very specific in their choice of substrates
{c} They are needed in large quantities
2. To what category of molecules do enzymes belong?
{A} carbohydrates {b} Lipids {c} Nucleic acids {D} Proteins
3. What is true about cofactors?
{A} Break hydrogen bonds in proteins {b} Help facilitate enzyme activity
{c} Increase activation energy {D}are composed of proteins
4. Prosthetic groups are________.
{A} Required by all enzyme {b} loosely attached with enzymes
{c} Proteins in nature {D} Tightly bounded to enzymes
5. When we add more substrate to an already occurring enzymatic reaction and there
is no increase in the rate of reaction, what would you predict?
{A} All active sites have been occupied by substrate molecules
{b} The enzyme molecules have been denatured
{c} More substrate acted as inhibitor
{D} More substrate has disturbed the pH of the medium
6. The termMetabolism is derived froma __________________ word?
{A} Latin {b} Greek {c} English {D} French
7. The termmetabolism is derived fromGreek word meaning ________
{A} challenge {b} energy {c} change {D} life
8. The concept of metabolism was first given by ______________.
{A} Ibn-e-Al-Hashim {b} Ibn-e-Nafees
{c} Emil Fisher {D} Danial Koshlan
9. In _______German physiologist Winhelm Kuhne first used the term enzyme
{A} 1878 {b} 1887 {c} 1885 {D} 1877
10. In 1878 German physiologist ____________first used the term enzyme
{A} Ibn-e-Nafees {b} Winhelm Kuhne
{c} Danial Koshland {D} Emil Fisher
CH-(6) MCQ’S

2. 2 S.S.A ( Siddique Science Academy)
10/C officers Colony Bahawalnagar ( Contect# 03338810387, 03000831969)
Prepared by;Miss ANZAL FAIQA YOUSUF (M.S.c BOTANY I.U.B)
BIOLOGY 9Th
11. The optimum temperature for the maximum working speed of human enzymes_
{A} 47 C0
{b} 57 C0
{c} 37 C0
{D} 87 C0
12. Lock and key model was purposed by _______.
{A} Danial Koshland {b} Emil Fisher
{c} Winhelm Kuhne {D} Ibn-e-Nafees
13. Lock and key model was purposed by a German chemist Emil Fisher in ___
{A} 1894 {b} 1994 {c} 1849 {D} 1949
14. Induced-fit model was purposed by _____________.
{A} Danial Koshland {b} Emil Fisher
{c} Winhelm Kuhne {D} Ibn-e-Nafees
15. Induced-fit model was purposed by Danial koshland in _____________.
{A} 1985 {b} 1858
{c} 1958 {D} 1885
16. There are about _________known enzyme.
{A} 20000 {b} 2000 {c} 1200 {D} 200
Q1: Define metabolism?
Ans: Metabolism is the set of biochemical reactions that occur in living organisms in
order to maintain life.
Q2: Define anabolism?
Ans: Anabolism includes the biochemical reactions in which larger molecules are
synthesized.
Q3: Define catabolism?
Ans: Catabolism includes the biochemical reactions in which larger molecules are
broken down.
Q4: Define activation Energy?
Ans: It is defined as minimum energy required to start a reaction. The need for
activation energy acts as a barrier to the beginning of the reaction.
Q5: Define Biocatalysts?
Ans: Enzymes are crucial to metabolism because they act as biocatalysts and
speed up and regulate metabolic pathways.
Ch#(6)Give Short Answers

3. 3 S.S.A ( Siddique Science Academy)
10/C officers Colony Bahawalnagar ( Contect# 03338810387, 03000831969)
Prepared by;Miss ANZAL FAIQA YOUSUF (M.S.c BOTANY I.U.B)
BIOLOGY 9Th
Q6: Define Substrates?
Ans: The molecules at which enzymes act are called substrates.
Q7: Define products?
Ans: Enzymes convert substrates in to different molecules called products
8: Define Biocatalysts?
Ans: Enzymes are proteins that catalyze biochemical reaction and are not changed
during the reaction
Q9: How enzymes lower the activation energy?
Ans: Enzymes lower the activation energy in several ways;
1. They may alter the shape of substrate and reduce the requirements of energy for
this change.
2. Some enzymes do so by disrupting the charge distribution on Substrates.
3. Enzymes may also lower activation energy by bringing substrates in the correct
orientation to react.
Q10: Define Intracellular and Extracellular enzymes?
Ans: Intracellular enzymes synthesized within the cell and also act within the cell.
While extracellular enzymes synthesized within the cell and act outside the cell.
Q12: Define denaturation?
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.
Q13: Define lock and key model?
Ans: According to this model, both enzymes and substrate possess a specific shape
that fit exactly in to one another. This model explains enzyme specificity.
Q14: Define induced-fit model?
Ans: According to this model, active site is not a rigid structure rather it is molded in
to the required shape to perform its function. It is more acceptable than “Lock and
key” model of enzyme action.
Q15: Define cofactors?
Ans: Some enzymes do not need any additional components to work. However
others require non-protein molecules or ions called cofactors. e.g. metal ions and
flavin.

4. 4 S.S.A ( Siddique Science Academy)
10/C officers Colony Bahawalnagar ( Contect# 03338810387, 03000831969)
Prepared by;Miss ANZAL FAIQA YOUSUF (M.S.c BOTANY I.U.B)
BIOLOGY 9Th
Q16: Define coenzyme?
Ans: If organic cofactors are loosely attached with enzymes they are called
coenzymes. They transport chemical groups from one enzyme to another e.g.
thiamine and folic acid.
Q17: Define prosthetics groups?
Ans: If organic cofactors are tightly bound to enzyme, they are called prosthetic
groups.
Q18: Define metabolic pathways?
Ans: Several enzymes can work together in a specific order, creating metabolic
pathways, in which enzyme takes the products of another enzyme as a substrate.
Q19: Define active site?
Ans: Only a small portion of enzyme molecule is directly involved in catalysis. This
catalytic region is known as active site.
Q20: Write 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; similarly lipase enzyme acts only on lipids and digests them in to
fatty acids and glycerol. Specificity of different enzymes is determined by the shapes
of their active sites which possess specific geometric shapes that fit with specific
substrates.
Q21: Mechanisms of Enzyme actions
Ans: When enzyme attaches with substrate, a temporary enzyme-substrate (ES)
complex is formed. Enzyme catalyzes the reaction and the substrate is transformed
in to product. After it, the ES complex breaks and enzyme and product are released.
E+S ES complex E+P

5. 5 S.S.A ( Siddique Science Academy)
10/C officers Colony Bahawalnagar ( Contect# 03338810387, 03000831969)
Prepared by;Miss ANZAL FAIQA YOUSUF (M.S.c BOTANY I.U.B)
BIOLOGY 9Th
Q1: Write the uses of enzymes?
Ans: Enzymes are extensively used in different industries for fast chemical reaction
e.g.;
 Food Industry: Enzymes that break starch in to simple sugar are used in the
production of white bread, buns etc
 Brewing Industry: Enzymes break starch and proteins. The products are used
by yeast for fermentation to produce alcohol
 Paper Industry: Enzymes break starch to lower its viscosity that aids in making
paper.
 Biological detergents Protease enzymes are used for the removal of protein
stains from clothes. Amylases are used in dish washing to remove resistant
starch residues.
Q2: Write Characteristics of Enzymes?
Ans: some of the characteristics of enzymes are as follow:
1. Almost all enzymes are proteins i.e. they are made of amino acids.
2. Most enzymes reaction rates are millions of times faster than those of
comparable uncatalyzed reactions. As with all catalysts, enzymes are not
consumed by the reactions they catalyze.
3. Enzymes are usually very specific for the type of reactions and for the nature of
their substrates.
4. Only a small portion of enzyme molecule is directly involved in catalyses. This
catalytic region is known as active site. It recognizes and binds substrate and
then carries out reactions.
5. Enzymes production can be enhanced or diminished by a cell according to
needs. Enzymes activity can also be regulated by inhibitors and activators.
6. Some enzymes do not need any additional components to work. However, others
required non-protein molecules or ions called cofactors. If cofactors are tightly
bond they are called prosthetics groups, if loosely attached they are called
coenzymes.
7. Several enzymes can work together in a specific order, creating metabolic
pathways, in which one enzyme takes the product of another enzyme as
substrate. After the reaction, the product is passed on to the next enzyme.
Ch-(6) LONG QUESTIONS

6. 6 S.S.A ( Siddique Science Academy)
10/C officers Colony Bahawalnagar ( Contect# 03338810387, 03000831969)
Prepared by;Miss ANZAL FAIQA YOUSUF (M.S.c BOTANY I.U.B)
BIOLOGY 9Th
Q3: Write the factors affecting the rate of enzyme action.
Ans: some of the factors are as follow;
1-Temperature:
Increase in temperature speeds up the rate of enzyme catalyzed
reactions. Every enzyme works at its maximum rate at a specific temperature called
as the optimum temperature for enzyme. 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 denaturation of enzyme. It
results in a rapid decrease in rate of enzyme action and it may be blocked
completely.
2-Substrate concentration:
If enzyme molecules are available in a reaction, increase in
substrate concentration increases the rate of reaction. If enzyme concentration is
kept constants and amount of substrates is increased, a point is reached where any
further increase in substrate does not increase the rate of reaction any more .When
the active sites of all enzymes are occupied, any more substrate molecules do not
find free active sites. This state is called saturation of active sites and reaction rate
does not increases
3- pH: All enzymes work at their maximum rate at a narrow range of pH, called as
the optimum pH. A sight changes in this pH causes retardation in enzyme activity or
blocks it completely. Every enzyme has a specific optimum pH value. e.g. pepsin
working in stomach is active in acidic medium(Low pH), while trypsin working small
intestine shows its activity in alkaline medium (high pH).Change in pH can affect the
ionization of the amino acids at the active site.