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BIO521S-IBC521S - BIOCHEMISTRY-INTRODUCTION TO BIOCHEMISTRY - 1ST OPP - NOV 2022 |
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nAmlBIA
UnlVERSITY
OF SCIEnCE Ano TECHnOLOGY
FACULTYOF HEALTH,NATURALRESOURCESAND APPLIEDSCIENCES
DEPARTMENTOF HEALTHSCIENCES
QUALIFICATION: BACHELOR OF MEDICAL LABORATORY SCIENCES/BACHELOR OF HUMAN
NUTRITION
QUALIFICATIONCODE: 08BMLS/08BOHN
LEVEL:5
COURSE: BIOCHEMISTRY/INTRODUCTION TO
BIOCHEMISTRY
SESSION:NOVEMBER 2022
DURATION: 3 HOURS
COURSECODE: BIO521S/IBC521S
PAPER:THEORY
MARKS: 120
FIRSTOPPORTUNITYEXAMINATION QUESTION PAPER
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 of the following domains contains the most primitive bacteria that live in (1)
extreme environments?
a. Archaea
b. Bacteria
c. Plantae
d. Eukarya
1.2 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
1.3 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
1.4 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
1.5 Which of these amino acids does not have optical isomer(s)
(1)
a. Alanine
b. Histidine
c. Threonine
d. Glycine
1.6 The following forces may play a role in the formation of quaternary structure (1)
EXCEPT
a. Hydrogen bonds
b. Disulphide bridges
c. Electrostatic interactions
d. Peptide bonds
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1.7 In phenylketonuria (PKU), the compound accumulated in the urine is
(1)
a. Homocysteine
b. Tryptophan
C. a-keto acid
d. Phenylpyruvate
1.8 Thyroxine is derived from
(1)
a. Thiamine
b. Threonine
C. Tyrosine
d. Tryptophan
1.9 The reactions of the urea cycle occur in
(1)
a. Cytosol
b. Mitochondrial matrix
C. Lysosome
d. Mitochondrial matrix and the cytosol
1.10 The major source of ammonia in the kidneys is
(1)
a. Glutamine
b. Alanine
C. Creatinine
d. Leucine
1.11 Which of these serum enzyme activities rises 4-8 hours after acute (1)
myocardial infarction (AMI)?
a. AST
b. ALT
c. CKMB
d. LDH
1.12 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
1.13 Pancreatic a -amylase
(1)
a. Hydrolyses starch completely to glucose
b. Hydrolyses a -dextrins
c. Hydrolyses a (1 ..-.4) glycosidic bonds
d. Is secreted as a zymogen
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1.14 All the following are composed of glucose EXCEPT
(1)
a. Amylase
b. Glycogen
C. Maltose
d. lnulin
1.15 Fructose is
(1)
a. A ketose sugar
b. A pentose
C. A sugar that requires insulin for its absorption
d. Phosphorylated by a phosphatase
1.16 D-Galactose and D-mannose are a pair of
(1)
a. Enantiomers
b. Isomers
C. Epimers
d. Anomers
1.17 In 13-oxidation of fatty acids, which of the following are utilised as
(1)
co-enzymes?
a. FAD and NAD+
b. FAD H2and NADH +W
C. NAD+and NADP+
d. FAD and FMN
1.18 A deficiency of carnitine might interfere with
(1)
a. rs-oxidation
b. Palmitate synthesis
C. Mobilisation of stored triacylglycerol from adipose tissue
d. Ketone body formation
1.19 Which of the following is an essential fatty acid?
(1)
a. Linolenic acid
b. Linoleic acid
C. Arachidonic acid
d. All above
1.20 Pancreatic lipase converts triacylglycerols into
(1)
a. 2-Monoacylglycerol
b. 3-Monoacylglycerol
C. 1-Monoacylglycerol
d. 2, 3-Diacylglycerol
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SECTION B
[100]
Question 2: Fill the blank spaces only by writing down the number and the correct (20)
missing expression (1 mark per correct answer).
2.1 Deamination of an amino acid is coupled with amination of ____
_
acid.
2.2 To form polypeptides and proteins, amino acids are joined together
by_____
bonds.
2.3 _____
are long, rod-shaped molecules that are insoluble in water and
physically tough.
2.4 The _____
concentration that produces half the maximal velocity
(Vmax/2) is known as Michaelis constant.
2.5 Substances that decrease the catalytic activity of enzymes are called
2.6 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.
2.7 Catalytic efficiency of enzymes can be regulated by _____
or
inhibition.
2.8 Enzymes may be termed as 'molecular switches', which regulate the
catalytic activity and transfer of _____
in the biological system.
2.9 _____
is present in the exoskeleton of invertebrates such as crabs,
lobsters and insects.
2.10 _____
is the most abundant carbohydrate in nature.
2.11 In diabetic patients, the accumulation of _____
in lens of the eye
leads to development of cataract.
2.12 Carbohydrates not only serve as major sources of energy but also function
as _____
for the synthesis of lipids, amino acids, glycoproteins and
proteoglycans in the body.
2.13 _____
are formed by interaction between a monosaccharide or a
monosaccharide residue and the hydroxyl group of a second compound that
may or may not be a monosaccharide.
2.14 _____
is the disease in which lactate, the final product of anaerobic
glycolysis, accumulates.
2.15 -----
levels.
is a condition were ketone bodies in blood rise above normal
2.16 Phospholipids are major components of cell membranes. They are also part
of lipoproteins and bile and act as lung____
_
2.17 Biosynthesis of cellular nucleic acids is largely dependent on the
_____
synthesis of nitrogenous bases, namely purines and
pyrimidines.
3.1~ Sphingolipids are involved in intracellular communication and as
_____
determinants of the ABO blood groups.
2.19 _____
is characterized by an elevated serum urate, which could be
due to a renal disorder.
2.20 Cholesterol molecule has _____
carbon atoms.
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(20)
Question 3: Match the correct expressions or definitions by writing down the
number and the letter only (1 mark per correct answer).
a. Fehling's
b. Epimers
C. Cholesterol
d. Glycogen
e. Enantiomers
f. Cellulose
g. Lectins
h. Catalytic
i. Axial
j. Glycoproteins
k. Golgi bodies
I. Amphoteric properties
m. A buffer
n. Albinism
o. Amphipathic
p. Amphipathic
q. Phenylalanine hydroxylase
r. Michaelis-Menten constant
s. Dissociation constant
t. Organic solvent
u. Phospholipid
v. Prokaryotes
w. Glycolipid
X. pH
y. lsoenzymes
z. Glycolipid
aa. apoenzyme
3.1 _____
These are stereoisomers that are mirror images of each other
which are bound by a membrane.
3.2 ______
These monosaccharides differ at a single asymmetric carbon.
3.3 Proteins produced by the ribosomes are stored in the form of secretory
granules in the ------
3.4 ______
This is the most abundant organic molecule in the biosphere.
3.5 ______
This is a test solution used to identify reducing and
nonreducing sugars.
3.6 _____
The storage form of glucose in animals.
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
_____
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).
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.
3.18 A lipid is defined as a compound soluble in -------
3.19 Lipids which contain carbohydrates are ____
_
3.20 _____
: A type of lipid with two acyl chains, a glycerol backbone, and
a polar head group.
Question 4: Short Answers
(40)
4.1 Name the four buffer systems in the body.
(4)
4.2 What is the difference between holoenzyme, apoenzyme and abzyme?
(3)
4.3 Name the amino acids which are glycogenic and ketogenic.
(4)
4.4 Name the tests which detect the following amino acids: aromatic,
(5)
tryptophan, arginine, a-amino acids, and tyrosine.
4.5 Answer the following questions on metabolic alkalosis
a. What is metabolic alkalosis?
(2)
b. When does it occur?
{2)
c. How will metabolic alkalosis be compensated by the human body?
(2)
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4.6 Answer the following questions on carbohydrate metabolism
a. Define gluconeogenesis
(2)
b. What is Cori cycle and explain the events that place in that cycle?
(4)
c. What are the irreversible steps of glycolysis and name the enzymes
(6)
involved in these steps?
4.7 Answer the following questions on lipids and fatty acids metabolism
a. What is the importance of ketone bodies as fuels?
(2)
b. Which enzyme is absent in adipose tissue?
(2)
c. What is the role of bile salts?
(2)
(20)
Question 5: Calculation
5.1 What is the pH of the following solutions?
a. 0.35 M hydrochloric acid
(2)
b. 0.35 M acetic acid (pKa = 4.76)
(3)
5.2 A weak acid, HA, has a total concentration of 0.20M and is ionized (dissociated) (5)
to2%
5.3 A solution is labeled "0.450 M NaN3. Calculate the following [N31-J, [OH1-1, (5)
[HN3],and the pH of the solution? Express your concentrations to three
significant figures. Note that Kafor HN3= 1.9x10-05•
5.4 What is the pH of a buffer that is 0.12 Min lactic acid [CH3CH(OH)COOHo, r (5)
HC3HsO3a] nd 0.10 Min sodium lactate [CH3CH(OH)COONaor NaC3HsO3]?
lactic acid, Ka=1.4 x 10-4
THEEND
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