School of Health Sciences
DEPARTMENT OF DIETETICS, NUTRITION & BIOLOGICAL SCIENCES
BSc (Hons) Applied Pharmacology
BSc (Hons) Human Biology
BSc (Hons) Dietetics
BSc (Hons) Human Nutrition
LEVEL 1
BIOCHEMISTRY I – D1129
Diet 1
DATE:
12 Jan 09
TIME: 2.30pm
DURATION: 2 Hours
READING TIME: 5 mins
MATRICULATION NUMBER -……………………………………….
INSTRUCTIONS:
THERE ARE 3 SECTIONS IN THIS PAPER:
PLEASE ANSWER ALL QUESTIONS IN SECTION A ON THE EXAM PAPER.
ANSWER ALL QUESTIONS IN SECTION B AND THREE QUESTIONS FROM
SECTION C IN THE BOOKLET PROVIDED.
A PERIODIC TABLE AND A LIST OF AMINO ACIDS WILL BE SUPPLIED. YOU
WILL NEED THE USE OF A POCKET CALCULATOR.
1
PAPER SETTER:
Dr EMAD AL-DUJAILI
Section A: Answer all questions
1. Circle the correct answer from each of the following:
Mark
1. Valency of an element is
1
a) the number of electrons that have to be gained to fill the outer orbit
b) the number of electrons that have to be lost to empty the outer orbit
c) the number of electrons that have to be shared between 2 elements
d) all the above
2. All these are examples of hydrophobic amino acids except:
a) alanine
b) aspartic acid
c) tryptophan
d) valine
3. What is the pH of lemonade (0.0001 molar H+ concentration)?
a)
b)
c)
d)
1
the [OH-] is less than the [H+]
the [OH-] is equal to the [H+]
the [OH-] is greater than the [H+]
none of the above
5. What is the total concentration of all ions in a 0.25 Molar solution of Na2SO4?
a)
b)
c)
d)
1
2
3
4
5
4. In an alkaline solution:
a)
b)
c)
d)
1
1
0.25 M
0.50 M
0.75 M
1.0 M
6. Which compound is the most polar?
a) pentanol
b) propane
c) propanol
d) vegetable oil
1
7. What is the mass of 0.25 M of sodium carbonate?
a) 25.5 g
1
2
b)
c)
d)
26.5 g
27.5 g
28.5 g
8. Water is a good universal solvent because
a)
b)
c)
d)
1
it is an inorganic molecule
it is slightly acidic
it is a polar molecule
It is slightly alkaline
9. If you dissolve 0.8 g of sodium hydroxide in water to make a 0.25 M solution,
what volume is the solution?
a)
b)
c)
d)
1
100 mL
80 mL
60 mL
40 mL
10. Which compounds are positional isomers
a)
b)
c)
d)
11. Which compound when dissolved in water produces the highest pH value?
a)
b)
c)
d)
1
methanoic acid and ethanoic acid
methanol and methanal
1-pentanol and 3-pentanol
ethane and ethanol
1
0.1 M sodium ethanoate
100 mM ammonia
10 mM ammonia
100 mM ammonium ion
12. Which of the following compounds would you expect to be most soluble in
water?
1
a) CH3-CH2-OH
b) CH3-CH2-CH2-OH
c) CH3-CH2-CH2-CH2-OH
d) CH3-CH2-CH2-CH2-CH2-OH
13. Which of the following is the conjugate base of H2PO4- ?
a)
b)
c)
d)
1
H3PO4
HPO4 HPO42PO43-
3
14. Buffer can be prepared by mixing:
a. a strong acid and its conjugate base.
b. a strong base and its conjugate acid.
c. a weak acid and its conjugate base.
d. a weak acid and a strong acid.
1
15. What is the pH of a buffer solution containing 0.30 M NH3 and 0.10 M NH4Cl?
[pKa=9.2]
1
a)
b)
c)
d)
8.77
9.25
9.73
5.22
16. For what pH range could you use a mixture of KH2PO4 and K2HPO4 to make a
buffer solution (pKa =7.2)?
1
a) pH 2.12 - 12.32
b) pH 1.12 - 3.12
c) pH 11.32 - 13.3
e) pH 6.21-8.21
17. How many moles of glucose are contained in 500mL of 0.30 M glucose used in
intravenous injection?
1
a) 0.015
b) 0.15
c) 0.06
d) 0.6
18. Determine the mass (g) of solute required to form 500.0 mL of a 0.480 M
MgCl2
a) 24.2
b) 26.4
c) 22.8
d) 19.8
1
19. What is the pH of a sample of gastric juice whose hydrogen ion concentration
is 4.5 x 10-2 M?
1
a)
b)
c)
d)
1.15
1.65
0.65
2.35
4
20. What is the pH of a solution of 0.65 M acid and 0.51 M of its conjugate base if
the pKa = 5.30?
1
a) 6.05
b) 5.19
c) 5.41
d) 5.85
e) 5.62
21. Cow's milk contains an average of 4.5 g of lactose, C12H22O11, per litre. What is
the molarity of lactose in milk?
1
a) 0.017
b) 0.17
c) 0.13
d) 0.013
22. The correct formula for the compound formed from aluminum ions and
hydroxide ions is
1
a)
b)
c)
d)
AlOH
AlOH2
Al(OH)3
AlOH2
23. Redox reactions occur in aqueous solution when
1
a) a transfer of protons takes place.
b) a transfer of electron pairs occurs.
c) a transfer of one or more electrons occurs.
d) No transfer of protons or electrons
24. A solution is prepared by dissolving 10.0 g of NaOH in sufficient H2O to produce
250 mL of solution. Calculate the molarity of this solution.
1
a)
b)
c)
d)
0.250 M
0.500 M
0.750 M
1.00 M
25. Ionic bonds result from
a) the transfer of protons from one nonmetal to another
b) the transfer of electrons from one nonmetal to another
c) the transfer of electrons from a metal to a nonmetal
d) the transfer of protons from a nonmetal to a metal
1
5
26. Covalent bonds form when
a)
b)
c)
d)
1
metals react with nonmetals.
metals react with one another.
nonmetals including hydrogen react with one another
transition metals react with metals
27. Which formula represents an organic acid
1
a) KOH
b) CH3 OH
c) CuSO4
d) CH3 CH2COOH
28. An isotope
1
a) has the same atomic mass and number as the parent element
b) has different atomic mass and number from the parent element
c) has the same atomic number and different atomic mass
d) has the same number of neutrons as the parent element
29. Which formula represents a salt
1
a) NaOH
b) HNO3
c) MgSO4
d) CH3CH2OH
30. Which of these compounds are associated with iron in the body
1
a) Haemoglobin and myoglobin
b) Ferritin and homosiderin
c) trasnsferrin
d) all the above
6
Section B: Answer all questions in the booklet provided
1. Convert the following to the most convenient units.
a)
b)
c)
d)
e)
f)
3
0.0000085 mg
0.00000925 m
0.00285 L
0.0000000085 g
0.00000175 mmole/L
95,000,000 pg
2. Briefly explain what is meant by the following terms and give one example in
each case:
a)
b)
c)
d)
e)
f)
9
Hydration shell
Redox reactions
Hydrolysis reactions
Biological buffer
Stereoisomerism
Condensation reactions
3. Short answer questions:
a) Is an aqueous solution of the salt (CH3NH3)Cl acidic, basic, or neutral and state
why?
1
b) Is an aqueous solution of the salt CH3COONa acidic, basic, or neutral and state
why?
1
c)What are the three factors involved in determining the effectiveness of a buffer? 1
d) From the list of amino acids, draw the structure of aspartic acid at neutral, acidic
and alkaline pH.
1
e) Explain briefly how the ammonium buffer can correct the pH of urine.
1
e) The blood buffer system is made up of H2CO3 and HCO3. Describe with the use
of equations how this system respond to added H + and to added OH 3
4. Phosphoric acid is an important building block of many biological
molecules.
a) Write three dissociation equations showing the formation of various phosphate
anions.
3
b) Identify the anions behaving like acids in the body and state why.
1
c) State two roles of phosphate in the human body.
1
7
Section C: Answer any Three questions from the following in the answer
booklet provided.
1. A biologist regularly uses a buffer solution that contains Na2HPO4 (50mM), and
NaH2PO4 (50mM) in his lab (pKa=7.0). Write a balanced chemical equation
showing the reaction that takes place when:
(a) 10mM sodium hydroxide, NaOH, is added to the buffer. Calculate the
new pH.
2
(b) 10mM hydrochloric acid, HCl, is added to the buffer. Calculate the
new pH
2
(c) Calculate the pH of the original buffer using the equation:
1
pH = pKa + log  conjugate base
 acid
2. Answer the following:
a) If the pKa for carbonic acid in blood = 6.1, bicarbonate ion = 19.8 mM and
potential acid = 1.35 mM. Calculate the pH of the blood sample.
b) Describe briefly how biological fluids solubilise bio-molecules
2
1
c) Explain briefly the importance of four of the following metals in biology: Zinc,
Copper, Selenium, Cobalt, Magnesium or Iron
2
3. Answer the following:
a) Draw the structure of the following:
i.
2-phospho-3-hydroxy-4-hexanone
ii.
3-Amino-4-hydroxy-octanal
iii.
2,3-Dimethyl butanoic acid
b) For each compound above, give the number of stereoisomers and
explain why?
3
2
4. Answer the following:
a) Comment on the importance of stereoisomerism in bio-molecules.
1
b) Define the term “free radical” and comment on its effects on body organs.
2
c) Explain briefly why water is the ideal medium in biological fluids?
2
End of paper
8