Answers to UNIT 11 Self Test:

Part I: Matching

1.  ac        2. ad        3. bc        4. b        5. c        6. a        7. e        8. d        9. ab        10. ae

Part II: Multiple Choice

11. c; This is the alcohol because it contains the hydroxyl group.

12. a; Structural isomers have the same molecular formula but a different arrangement of the atoms, therefore the properties and structures are different.

13. a; This structure contains a carbonyl group but it is not on an end carbon, therefore it is a ketone and not an aldehyde.

14. b; This structure contains two oxygens and based upon the number of bonds to each carbon and oxygen there would be a carbonyl group with another oxygen singly bonded to the same carbon.  There is then an additional carbon bonded to that oxygen.  This is the ester functional group.

15. c; the alcohol is the most soluble in water since it is both polar and can hydrogen bond with water.

16. d; The structure C₂H₆ contains only single bonds and is saturated with hydrogens.

17. c; The functional group is the key to the organic molecules chemistry.  This is why we are studying them.

18. c; Esters typically have pleasant and even fruity smells.  They are the natural and synthetic molecules that give flavor and aroma to fruits, perfumes and artificial flavoring.

19. b; These  substances are all saccharides and therefore carbohydrates.

20. d; Alkanes (saturated hydrocarbons) can not hydrogen bond with water since none of the alkane's hydrogens are bonded to carbon; there are no oxygens, nitrogens or fluorines present.

21. b; Nucleic acids contain a phosphate ion.  This ion when covalently bonded into the DNA or RNA provides the link between the nucleotides.

22. b; The primary structure of a protein is based on the amino acid sequence.

23. c; Proteins' tertiary structure is the 3-D shape of the protein.

24. d; The formation of the double helix of DNA is the result of the hydrogen bonding between the nitrogenous bases on the opposite DNA strands.

25. d; Both esters and carboxylic acids have two oxygens and they contain a C==O double bond and thus have hydrogens in a 2:1 ratio with carbons.

26. b; Alcohols and carboxylic acids react in a dehydration synthesis reaction to produce an ester.

27. (a) AT    (b) NT    (c) AT    (d) ST    (e) AT

Part III: Problems:

28. (There are more than one possibility here.) (a) CH₃CH₂CH₂CH₂OH        (b) H₂C==CHCH₂CH(NH₂)CH₃

        (c) CH₃COOH        (d) CH₃COCH₂CH₃

29. (Carbon skeleton only given)  C-C-C-C-C-C        C-C-C-C-C        C-C-C-C-C        C-C-C-C
                                                                                                 |                       |                      |    |
                                                                                                C                     C                    C  C

30.  (a) CH₃--C--C*--C^*--CH₃         (b) CH₃--C*--C--CH₃  (whole structure not written)

31. CH₃CH₂CHO    CH₃COCH₃

32.  Amines, alcohols and carboxylic acids are all soluble in water, have high boiling points and are liquids at room temperature because of the particularly strong hydrogen bonding intermolecular force they exhibit between their molecules.

33. (a) These are structural isomers.        (b) These are optical isomers.    (c) [This was left blank in error.]

34. (a) -OOC- is the characteristic group of atoms in an ester.    (b) -OH is the hydroxyl group in an alcohol.
      (c) -NH₂ is the functional group of an amine.        (d) -CHO is a terminal carbonyl group of an aldehyde.

35.  Ethyl alcohol has the higher boiling point, is a liquid at room temperature and is more soluble in water all because of its ability to hydrogen bond with water.  Dimethyl ether is a polar molecule and exhibits dipole-dipole interactions with itself and with a polar solvent, but this intermolecular force is weaker than the hydrogen bonding in the alcohol.  This is the reason for the differences in their properties.

36.  Monosaccharides contain a single basic carbohydrate ring (or straight chain) such as glucose or ribose.  Disaccharides contain two monosaccharides such as sucrose (glucose and fructose) and maltose which consists of two glucose units.  Polysaccharides are natural polymers containing several monosaccharide units.  The most common of these are starch and cellulose.  Both of these are made up of glucose units.

37. Triglycerides, waxes and phospholipids are all lipids.  Triglycerides are triesters which contain glycerol, a three carbon, tri-alcohol) with three fatty acid chains linked by an ester bond to the glycerol.  The fatty acid chains are long with 16 or 18 carbons.  Plant triglycerides tend to contain unsaturated hydrocarbon, fatty acid chains whereas animal fatty acids contain saturated chains.  Phospholipids are diglycerides with only two fatty acid chains attached to a glycerol by the ester fuctional group.  On the third carbon in glycerol a phosphate group is attached.  Waxes are single esters with long chain hydrocarbons on the alcohol and acid ends of the ester functional group.  The general property of lipids is that they are usually water fearing, hydrophobic.  Triglycerides are very concentrated forms of energy storage.  Phospholipids form the basic components of the cell membrane and waxes are found in plants and animals as a water proofing coating.

38.Bonding in proteins takes place between amino acids.  The amino end of one amino acid reacts with the  carboxylic acid functional group on another amino acid forming a peptide bond and releasing a water molecule.

39.  (see notes)

40. (see classroom board)

41.  DNA and RNA are the two primary nucleic acids.  They are biopolymers made of nucleotide units.  Each nucleotide contains the monosaccharide, ribose, a phosphate group and a nitrogenous base.  DNA contains deoxyribose and RNA contains ribose.  DNA contains the nitrogenous base thymine, while RNA has uracil in stead of thymine.  DNA is a double helix whereas RNA is a single helix structure.

42. (a) Carbohydrates are the energy storage molecules in plants and the main energy source for animals.  Cellulose is also a structural molecule in plants, making up 50% of all organic matter in plants.

    (b) Lipids serve as energy storage molecules in animals and the phospholipids are the building blocks of the cell membrane.

    (c) Proteins can serve as structural components of living things and as enzymes, chemical catalysts to cell reactions.

    (d) Nucleic acids DNA encode all the information for making the essential proteins for cell's function.  RNA acts as the transporter of this information from the cell nucleus to the ribosome.  RNA also transports the amino acid units to the ribosome for protein synthesis.