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BIO521S-IBC521S - BIOCHEMISTRY-INTRODUCTION TO BIOCHEMISTRY - 2ND OPP - JAN 2023 |
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nAmlBIA
unlVERSITY
OF SCIEnCE Ano TECHnOLOGY
FACULTYOF HEALTH,NATURALRESOURCESAND APPLIEDSCIENCES
DEPARTMENT OF HEALTH SCIENCES
QUALIFICATION: BACHELOR OF MEDICAL LABORATORY SCIENCES/BACHELOR OF HUMAN
NUTRITION
QUALIFICATIONCODE: 08BMLS/08BOHN
LEVEL:5
COURSE: BIOCHEMISTRY/INTRODUCTION TO
BIOCHEMISTRY
SESSION:JANUARY 2023
DURATION: 3 HOURS
COURSECODE: BIO521S/IBC521S
PAPER:THEORY
MARKS: 120
SUPPLEMENTARY/ SECOND OPPORTUNITY EXAMINATION QUESTION PAPAER
EXAMINER
DR YAPO GUILLAUME ABOUA
MODERATOR: PROF HABAUKA KWAAMBWA
INSTRUCTIONS
1. Answer all questions.
2. Please write neatly and legibly.
3. Do not use the left side margin of the exam answer book.
4. No books, notes or other additional aids are allowed.
5. Mark all answers clearly with their respective question numbers.
Non-programmable calculator is allowed.
THIS QUESTION PAPERCONSISTSOF 8 PAGES(Including this front page)
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SECTIONA
[20]
Question 1: Multiple Choice
1.1 Which organisms obtain their food by absorption through filaments called (1)
hyphae?
a. Protista
b. Plantae
C. Archaea
d. Fungi
1.2 Which of the following kingdoms contains multicellular organisms that (1}
ingest their food?
a. Protista
b. Animalia
c. Plantae
d. Archaea
1.3 From the biological viewpoint, solutions can be grouped into
(1)
a. Isotonic solution
b. Hypotonic solutions
c. Hypertonic solution
d. All of these
1.4 ____
cells are cells that lack a membrane-bound nucleus.
(1}
a. Animal
b. Prokaryotic
c. Fungal
d. Eukaryotic
1.5 The kidneys contribute to acid-base balance by
(1)
a. Secretion of ammonia
b. Decreased carbon dioxide uptake
c. Regulating the pC02
d. Increased ketogenesis
1.6 pKa
a. Indicates the strength of an acid
(1)
b. Reflects the pH of the solution
c. Is a measure of the buffer capacity
d. Is high when the acid is weak
1.7 The normal pH of human blood is
(1)
a. 7.0-7.1
b. 7.25-7.3
C. 7.35-7.4
d. 7.5-7.55
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1.8 Compensatory response for respiratory alkalosis involves
(1)
a. Decrease in bicarbonate levels
b. Increase in bicarbonate levels
c. Decrease in pC02
d. Increase in pC02
1.9 Which of these amino acids does not have optical isomer(s)
(1)
a. Alanine
b. Histidine
c. Threonine
d. Glycine
1.10 The following forces may play a role in the formation of quaternary (1)
structure EXCEPT
a. Hydrogen bonds
b. Disulphide bridges
C. Electrostatic interactions
d. Peptide bonds
1.11 Insulin
a. is made up of two polypeptide chains
(1)
b. has four disulphide linkages
C. contains 55 amino acids
d. is a glycoprotein
1.12 The physiological pH amino acid solutions
a. contain both positive and negative charges
(1)
b. contain positively charged side chains
c. contain only positive charge
d. contain negatively charged side chains
1.13 In phenylketonuria (PKU),the compound accumulated in the urine is
(1)
a. Homocysteine
b. Tryptophan
c. a-keto acid
d. Phenylpyruvate
1.14 Thyroxine is derived from
(1)
a. Thiamine
b. Threonine
c. Tyrosine
d. Tryptophan
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1.15 The reactions of the urea cycle occur in
(1)
a. Cytosol
b. Mitochondrial matrix
c. Lysosome
d. Mitochondrial matrix and the cytosol
1.16 The major source of ammonia in the kidneys is
(1)
a. Glutamine
b. Alanine
c. Creatinine
d. Leucine
1.17 Denaturation of proteins results in
(1)
a. Disruption of primary structure
b. Breakdown of peptide bonds
c. Destruction of hydrogen bonds
d. Irreversible changes in the molecule
1.18 Which of these serum enzyme activities rises 4-8 hours after acute (1)
myocardial infarction (AMI)?
a. AST
b. ALT
c. CKMB
d. LOH
1.19 Enzymes increase reaction rates by
(1)
a. Altering the change in free energy of the reaction
b. Inhibiting the backward reaction
c. Enhancing the forward reaction
d. Decreasing the energy of activation
1.20 Enzyme activity regulation include the following except
(1)
a. Allosteric activation
b. Competitive inhibition
c. Suicide inhibition
d. Covalent modification
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SECTION B
[100]
Question 2: Fill the blank spaces only by writing down the number and the
correct missing expression (1 mark per correct answer).
(20)
2.1
2.2
2.3
2.4
2.5
2.6
2.7
2.8
2.9
2.10
2.11
2.12
-----
acid is the study that explains how different sequences
of biochemical reactions interact with each other for survival of cell
(organism) under various conditions.
In Induced Fit Model, the enzyme molecule of amino acid residues that
make up the _____
are not oriented properly in the absence of
substrate.
In spermatozoa, _____
accounts for 90% of cell whereas in other
cells, it accounts for less than 10% of the cell.
_____
amino acids are amino acids that can be converted to
glucose
When the CO2level in the blood rises (as it does when you hold your
breath), the excess CO2 reacts with water to form additional carbonic
acid and ____
blood pH.
Lactic acid enhances tissue oxyhaemoglobin dissociation and expansion
of the coronary vessels, therefore compensates
phenomena.
Amino acids are _____
for proteins.
Deamination of an amino acid is coupled with amination of
_____
acid.
To form polypeptides and proteins, amino acids are joined together by
-----
_____
bonds.
are long, rod-shaped molecules that are insoluble in water
and physically tough.
The _____
concentration that produces half the maximal velocity
(Vmax/2) is known as Michaelis constant.
Substances that decrease the catalytic activity of enzymes are called
2.13 One difference between 'chemical catalysts and enzymes is that
enzymes are _____
in the type of reaction to be catalysed and
they function within a moderate range of hydrogen ion concentration
and temperature along with certain other specified conditions.
2.14 Catalytic efficiency of enzymes can be regulated by _____
or
inhibition.
2.15 Enzymes may be termed as 'molecular switches', which regulate the
catalytic activity and transfer of _____
in the biological system.
2.16 Obesity is accumulation of _____
in the body.
2.17 Insulin decreases _____
in the liver.
3.lt Carbohydrates are defined as polyhydroxy derivatives of aldehydes or
2.19 _______
are polymers of the same monosaccharide units,
e.g. starch, glycogen, inulin, cellulose, dextrin, dextran.
2.20 _____
are stereoisomers that are mirror images of each other.
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Question 3: Match the correct expressionsor definitions by writing down the (20)
number and the letter only (1 mark per correct answer).
a. Essential amino acids
b. Mitochondria
C. Lectins
d. Glucogenic
e. Hydrolytic enzymes
f. Amino acids
g. Lectins
h. Catalytic
i. Axial
j. Glycoproteins
k. Golgi bodies
I. Amphoteric properties
m. A buffer
n. Albinism
o. Glycerophospholipids
p. Amphipathic
q. Phenylalanine hydroxylase
r. Michaelis-Menten constant
s. Dissociation constant
t. Cholesterol
u. Organic solvent
V. Prokaryotes
w. Amphipathic
x. pH
y. lsoenzymes
3.1 _____
are predominantly present in those subcellular organelles,
which are bound by a membrane.
3.2 ______
are called 'powerhouses' of the cell.
3.3 Proteins produced by the ribosomes are stored in the form of secretory
granules in the _____
_
3.4 ______
are the monomeric units, which are joined together to
form proteins.
3.5 ______
need to be supplied in the form of dietary proteins.
3.6 ______
amino acids yield pyruvate or any of the intermediates of
the TCA cycle.
3.7 ______
proteins act as biocatalysts in various metabolic
reactions, known as enzymes, e.g. hexokinase and lactate
dehydrogenase.
3.8 Proteins exhibit ______
. Each protein has an isoelectric pH at
which there is no net charge on the protein.
3.9 phenylketonuria is an inborn error of amino acid metabolism.
______
is the deficient enzyme.
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3.10
3.11
3.12
3.13
3.14
3.15
3.16
3.17
3.18
3.19
3.20
_____
occurs due to the deficiency of the enzyme tyrosinase.
Blood
plays a very important role in the maintenance of
body homeostasis.
_____
is defined as a solution which resists a change in pH
when an acid or a base is added.
pKa is the negative logarithm of the _____
of a weak acid.
_____
is the characteristic of an enzyme at any given pH and
temperature. It helps to evaluate the affinity of the enzyme towards
its substrate.
_____
are enzymes that catalyse the same chemical reaction,
but differ from each other structurally, electrophoretically and
immunologically (e.g LDH).
_____
These proteins bind to specific carbohydrate structures.
The storage form of fatty acids is ____
_
In addition to phospholipids and glycolipids, ___ is a major type of
membrane lipid.
_____
: A term applied to molecules that have both hydrophilic
and hydrophobic moieties.
A lipid is defined as a compound soluble in -------
Question 4: Short Answers
(40}
4.1 The major carbohydrates present in our diet are starch, glycogen, sucrose,
lactose, maltose and very little concentrations of fructose and pentose.
a. Describe the structures and functions of chitin and starch.
(4)
b. State briefly four regulation processes of blood glucose.
(4)
c. What are the structural differences between maltose, sucrose and (3)
lactose?
d. Name the three enzymes involved in the process of gluconeogenesis. (3)
e. Why is a Citric Acid Cycle said to be an anaplerotic process?
(2)
f. What is glycogenolysis?
(2)
4.2 The animal sources of protein and lipids include milk, butter, ghee, meat,
and fish.
a. Explain the difference between oil and fat.
(2)
b. What are prostaglandins and what is its precursor?
(3)
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C. Name two polyunsaturated fatty acids (PUFAs}
(2)
d. Name three constituents of cephalin and three constituents for lecithin (6)
e. Name three glucogenic amino acids.
(3)
f. What is known as animal starch? What is it structural particularity?
(2)
g. What is Cori cycle and explain the events that place in that cycle?
(4}
[20]
Question 5: Calculation
5.1 A solution of a certain weakly acidic substance was prepared by
dissolving and diluting 2.344 g to a final volume of 100 ml. In a
titration, 42.6 ml of 0.250 M NaOH solution was required to reach a
successful endpoint. The shape of the titration curve was used for the
assumption that the acid was monoprotic. The pH at the endpoint was
9.4.
a. Calculate the apparent molecular weight of the unknown acid.
(2}
b. Calculate the Kafor the acidic substance.
(3)
c. Calculate the pH of the original 100 ml solution (prior to titration).
(2)
d. Calculate the pH at the midpoint of the titration (after addition of 21.3 (2)
ml of the sodium hydroxide solution).
3.2
A solution of 25.8 ml of 0.328 M sodium hydroxide is required to titrate
50.0 ml of sulfuric acid. Calculate the concentration of the acid
(3)
5.3. A windscreen washing liquid contains 2.00 g/l ammonia. What is the
pH of this liquid? The molecular weight of NH3=17 g/mol
(3)
5.4. You need to prepare a buffer solution at pH= 7.00 with KH2PO4 and
(5)
Na2HPO4.What would be the respective concentration of these
substances if you wished to obtain a final phosphate concentration
([HPO4"2] + [H2PO41·]) of a.3M?
THEEND
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