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BIO521S-IBC521S-INTRODUCTION TO BIOCHEMISTRY-JAN 2020 |
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NAMIBIA UNIVERSITY
OF SCIENCE AND TECHNOLOGY
Faculty of Health and Applied Sciences
Department of Health Sciences
QUALIFICATION: BACHELOR OF MEDICAL LABORATORY SCIENCES/BACHELOR OF HUMAN NUTRITION
QUALIFICATION CODE: O8BMLS/O8BOHN
LEVEL: 5
COURSE: BIOCHEMISTRY/INTRODUCTION TO BIOCHEMISTRY | COURSE CODE: BIO521S/IBC521S
SESSION: JANUARY 2020
DURATION: 3 HOURS
PAPER: THEORY
MARKS: 100
SUPPLEMENTARY/SECOND OPPORTUNITY EXAMINATION QUESTION PAPER
EXAMINER
DR YAPO GUILLAUME ABOUA
MODERATOR:
PROF HABAUKA KWAAMBWA
INSTRUCTIONS
Answer all questions.
Please write neatly and legibly.
Do not use the left side margin of the exam answer book.
No books, notes or other additional aids are allowed.
Mark all answers clearly with their respective question numbers.
Non-programmable calculator is allowed.
THIS QUESTION PAPER CONSISTS OF 8 PAGES (Including this front page)
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SECTION A
[20]
Question 1: Multiple Choice
1.1 Which of the following sequences of organisation is likely to be seen ina (1)
multicellular organism, going from smallest to largest?
a. Cell, organ, system, tissue
b. Cell, tissue, system, organism
c. Organism, system, organ, tissue
d. Tissue, system, cell, organ
1.2
Metal oxides are typically
while non-metal oxides are typically
(1)
a. Amphoteric, basic
b. Amphoteric, acidic
c. Basic, acidic
d. Basic, amphoteric
1.3 Anion gap is the difference in the plasma concentrations of
(1)
a. (Chloride) and (Bicarbonate)
b. (Sum of cations) and (Sum of anions)
c. (Sodium) and (Chloride)
d. (Sodium + Potassium) and (Chloride + Bicarbonate)
1.4 Name the amino acid which exists in two non-superimposable mirror
(1)
images of each other.
a. Anomer
b. Chiral carbon
c. Epimer
d. Enantiomer
1,5 Which of the following below is an example of enzyme specificity?
(1)
a. Substrate specificity
b. Reaction specificity
c. Stereo specificity
d. All ofthese
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1.6 What type of interactions between molecules in a living organism is
(1)
strongest?
a. Electrostatic interaction
b. Covalent bond
c. Hydrogen bonding
d. Van der Waals forces
LiF Which of the amino acids below is the uncharged derivative of an acidic (1)
amino acid?
a. Serine
b. Tyrosine
c. Glutamine
d. Cysteine
(1)
1.8 Which of the following is an amino acid found in proteins?
a. Adenosine
b. Alanine
c. Adenine
d. Linoleic acid
(1)
1,9
Regulation of some enzymes by covalent modification involves addition
or removal of
a. Phosphate
b. Coenzyme
c. Sulphate
d. Acetate
1.10 Coenzyme is
(1)
a. Often a metal
b. Always an inorganic compound
c. Oftena vitamin
d. Always a protein
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1.11 In B-oxidation of fatty acids, which of the following are utilised as
(1)
co-enzymes?
a. FAD and NAD*
b. FAD H2 and NADH*H*
c. NAD* and NADP*
d. FAD and FMN
1.12 A deficiency of carnitine might interfere with
(1)
a. &-oxidation
b. Palmitate synthesis
c. Mobilisation of stored triacylglycerol from adipose tissue
d. Ketone body formation
113 Which of the following is an essential fatty acid?
(1)
a. Linolenic acid
b. Linoleic acid
c. Arachidonic acid
d. All above
1.14 Pancreatic lipase converts triacylglycerols into
(1)
a. 2-Monoacylglycerol
b. 3-Monoacylglycerol
c. 1-Monoacylglycerol
d. 2, 3-Diacylglycerol
1.15 Oxidation of fatty acids occurs
(1)
a. Inthe cytosol
b. In the matrix of mitochondria
c. On inner mitochondrial membrane
d. On the microsomes
1.16 The following are functions of prostaglandins except
(1)
a. Prevention of myocardial infraction
b. Lowering of blood pressure
c. Anti-inflammatory
d. Introduction of labour
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1.17. The following are called reducing sugars EXCEPT
(1)
a. Glucose
b. Lactose
c. Sucrose
d. Maltose
1.18 Which one of the following glycolytic enzymes is used in gluconeogenesis? (1)
a. Glucokinase
b. Pyruvate kinase
c. Aldolase
d. Phosphofructokinase
1.19 Codons are present on
(1)
a. DNA
b. mRNA
c. tRNA
d. rRNA
1.20 In humans, the main product of purines is
(1)
a. Ammonia
b. Uric acid
c. Urea
d. B-alanine
SECTION B
[80]
Question 2: Fill the blank spaces only by writing down the number and the [20]
correct missing expression
yme
is the study that explains how different sequences of (1)
biochemical reactions interact with each other for survival of cell (organism)
under various conditions.
2.2 In Induced Fit Model, the enzyme molecule of amino acid residues that make (1)
up the
are not oriented properly in the absence of substrate.
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2.3 In spermatozoa,
accounts for 90% of cell whereas in other cells, (1)
it accounts for less than 10% of the cell.
(1)
2.4
amino acids are amino acids that can be converted to glucose.
(1)
2.5 When the CO; level in the blood rises (as it does when you hold your breath),
the excess CO reacts with water to form additional carbonic acid and
blood pH.
2.6 Lactic acid enhances tissue oxyhaemoglobin dissociation and expansion of
the coronary vessels, therefore compensates
phenomena.
2.7 Amino acids are
for proteins.
2.8 Deamination of an amino acid is coupled with amination ofa ___ acid.
2.9 To form polypeptides and proteins, amino acids are joined together by
bonds.
2.10 Transcription continues until a
sequence is reached.
2.11
are long, rod-shaped molecules that are insoluble in water
and physically tough.
(1)
2.12 All inherited and expressed genetic information, involve processes such as
replication,
and translation into proteins.
(1)
2.13 One difference between ‘chemical catalysts’ and enzyme is that enzymes
are___ inthe 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
(1)
or
inhibition.
(1)
2.15 Enzymes may be termed as ‘molecular switches’, which regulate the
catalytic activity and transfer of
in the biological system.
(1)
2.16 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.
(1)
2.17
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.
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2.18
is the disease in which lactate, the final product of anaerobic
glycolysis, accumulates.
2.19
is a condition where ketone bodies in blood rise above normal (1)
levels.
2.20 Phospholipids are major components of cell membranes. They are also part (1)
of lipoproteins and bile and act as lung
Question 3: Short Answers
[40]
3.1 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 isa Citric Acid Cycle said to be an anaplerotic process?
(2)
3.2 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)
c. Why does butter soften at room temperature?
(2)
d. Why does coconut oil solidify in winter?
(2)
e. Name four biological functions of lipids.
(4)
f. Name four lipid components found in biological membranes.
(4)
g. State the position and functions of two types of membrane proteins.
(4)
h. Name three glucogenic amino acids?
(3)
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Question 4: Calculations
[20]
4.1. A buffer solution can be made by dissolving 0.25 g of sodium ethanoate in
200 cm? of 0.10 moldm®? ethanoic acid. Assume that the change in weight is
negligible.
a. Define the term buffer solution
(2)
b. Calculate the concentration of the sodium ethanoate.
(2)
c. Calculate the pH of the resulting buffer solution if Ka= 1.74 x 10°
(4)
4.2. During a practical exam, you were requested to prepare 1 L of a buffer
solution containing 0.10 M HCN and 0.12 M CN’. (Ka = 7.2 x 10°")
a. What is the pH of this buffer?
(2)
b. What is the pH if 0.01 mol of HCl is added to the buffer?
(2)
c. What is the pH if 0.02 mol of NaOH is added to the original buffer?
(3)
4.3 Calculate the fluoride ion concentration and pH of a solution that is0.20M (5)
in HF and 0.10 Min HCI. The equilibrium constant for the ionization of
HF is 6.8 x10%.
END OF EXAM