Download Islamic University of Gaza Biochemistry School of Nursing Midterm

Islamic University of Gaza
School of Nursing
Fall semester
Biochemistry
Midterm Exam
Date: 23/11/2010
Time: 1 Hour
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A. Choose the correct answer from the following.
(7 points)
1. Organic Chemistry is known otherwise as the chemistry of carbon compounds because:
a. Carbon is unique in forming hydrogen bonds with other carbon compounds
b. There are millions of organic compounds of nitrogen known
c. Carbon is unique in forming covalent bonds to other carbon atoms
d. None of the above
Answer: c
2. Compared to inorganic compounds, organic ones
a. Are not flammable
b. They have a higher melting point
c. Are soluble in water
d. Are soluble in nonpolar solvents
e. Their boiling point is lower than that of inorganic ones
f. Both d and e are correct.
Answer: f
3. Some allotropic forms of carbon include
a. Diamond b.
Graphite
c.
Fullerene
d.
a, b, c are all correct
Answer: d
4. The general formula for alkenes is
a. CnH2n+2
b. CnH2n-2
c. CnH2n+1
d. CnH2n
e. None of the above
Answer: d
5. Ethene is a plant hormone responsible for ripening of fruits. It has the following structure
a. CH3-CH3 b. CH2-CH3 c. CH2=CH3 d. CH2=CH2
e. both c and d are correct
Answer: d
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6. C12H22O11 (sucrose) can react with H2O to give:
a. Butyl alcohol b. Propanol
c. Methyl alcohol
Answer: d
d. Ethyl Alcohol
e. a & d
7. Which sentence about methanol is incorrect:
a. It is usually used as a solvent in industry.
b. Toxic if inhaled and should never be applied directly to the body
c. Commonly known as wood alcohol.
d. It can not be directly prepared from the distillation of wood
e. Commercially it is prepared from carbon monoxide.
f. None of the above
Answer: d
B. Decide whether the following sentences are correct/incorrect and correct the
incorrect ones if needed:
(10 points)
1. A structural formula shows the exact way in which the atoms are connected to each
other, but a molecular formula does not.
(correct)
2. You can tell the structure of a molecule from its molecular formula.
You cannot tell the structure…….etc.
( incorrect)
3. Isomers are defined as compounds having the same arrangement of atoms but different
molecular formula.
( incorrect)
……….a different arrangement of atoms……..but the same molecular formula
4. Carbon atoms can join together to form continuous or branched chains of carbon
atoms. Such compounds are called cyclic compounds
( incorrect)
Aliphatic compounds
5. Alkyl groups are obtained from alkane by changing the ending of the name from –one
to -ene
( incorrect)
From –ane to -yl
6. As the number of alkane carbon atoms increases, the boiling point but not the density
increases
(incorrect)
Boiling point and Density
Islamic University of Gaza
School of Nursing
Fall semester
Biochemistry
Midterm Exam
Date: 23/11/2010
Time: 1 Hour
7. Halothane which is used as an anesthetic, is a derivative of thiol
A hydrocarbon derivative
Or halogen derivatives of ethylmethyl ether
(incorrect)
8. If two carbon atoms are connected by a double bond, those two carbon atoms but not
the four groups attached to them, lie in a single plane
(incorrect)
All four groups and the 2 carbon atoms lie in a single plane
9. A tertiary alcohol is one in which the –OH is attached to a carbon atom that has three
or more carbon atoms attached to it.
(incorrect)
three
10. The product of the oxidation of a secondary alcohol is an aldehyde
ketone
(incorrect)
-----------------------------------------------------------------------------------------------C. Draw the structural formulas for the following:
1. C3H8O
(Total points: 23)
(3 points)
One of these isomers is a type of organic compound called an ether.
The other two isomers are a type of organic compound called alcohols.
-------------------------------------------------------------------------------------3
2. Give the possible structures of C2H6O. Name these compounds and decide whether they
have different properties?
(4 points)
Dimethyl ether
Ethanol
Alcohols and Ethers they have different properties
--------------------------------------------------------------------------------------3. Draw the structural formulas for C5H12
( 2 points)
Three isomers:
CH3-CH2-CH2-CH2-CH3
CH3-CH2-CH(CH3)-CH3
CH3C(CH3)2CH3
------------------------------------------------------------------------------4. Give six examples of medically important organic acids and talk about three of them in
details.
(3 points)
1. Formic Acid: Colorless with a sharp irritating odor. Found In the sting of bees and
ants. It causes the characteristic pain and swelling when injected into the tissues. Its is
one of the strongest organic acid.
2. Acetic Acid: Found in vinegar. The CH3-CHO (acetyl group) coming from the acetic
acid is of a great importance during metabolism in Krebs Cycle.
3. Citric Acid
4. Lactic Acid
5. Oxalic Acid: One of the strong, naturally occurring organic acids. Is used to remove
stains such as rust and potassium permanganate stains. Salt of oxalic acid prevent
Islamic University of Gaza
School of Nursing
Fall semester
Biochemistry
Midterm Exam
Date: 23/11/2010
Time: 1 Hour
clotting by chelating Ca+2 from the blood (only for analytical purposes). It should not
be added directly to bloodstream because it is poisonous.
6. Pyruvic Acid
7. Tartaric Acid
8. Stearic Acid
-----------------------------------------------------------------------------------5. Write the condensed structural formulas for C3H6Cl2
(4 points)
There are four isomers:
CH3CH2CHCl2
CH3CCl2CH3
CH3CHClCH2Cl
CH2ClCH2CH2Cl
-----------------------------------------------------------------------------6. Draw the structure of 2-methyl-2-propyl alcohol
(2 point)
-----------------------------------------------------------------------D. Briefly talk about the tests for aldehydes.
(3 points)
Aldehyde are good reducing agents. Based on this property of aldehydes to reduce Cu2+ to form
Cu1+, an application has found its way to the laboratory to test for glucose in urine sample, since
glucose is an aldehyde. When an aldehyde is heated with Benedict’s or Fehling’s solution, a red
precipitate of Cu1+ (Cu2O) is formed.
5
E. What are acetal and Ketal? Give the reactions that lead to their formation.
(2 points)
Acetal and Ketal are compounds that derive from the reaction of hemiacetal or Hemiketal
respectively with an alcohol. These structures are very important in disaccharides and
polysaccharides.
Hemiacetal + alcohol ----> Acetal + H2O
Hemiketal + alcohol -----> Ketal + H2O
----The End----
Dr. Tarek M. Zaida