| Date | May 2018 | Marks available | 2 | Reference code | 18M.3.sl.TZ2.7 |
| Level | SL | Paper | 3 | Time zone | TZ2 |
| Command term | Outline | Question number | 7 | Adapted from | N/A |
Question
Amino acids are the building blocks of proteins.
Draw the dipeptide represented by the formula Ala-Gly using section 33 of the data booklet.
[2]
a.
Deduce the number of 1H NMR signals produced by the zwitterion form of alanine.
[1]
b.
Outline why amino acids have high melting points.
[2]
c.
Markscheme
peptide bond
order of amino acids
Accept zwitterion form of dipeptide.
Accept a condensed structural formula or a skeletal structure.
Penalize missing hydrogens or incorrect bond connectivities once only in Option B.
[2 marks]
a.
3
[1 mark]
b.
form zwitterions
«strong» ionic bonding
OR
«strong» ionic lattice
OR
«strong» electrostatic attraction/forces
Do not accept hydrogen bonding or IMFs for M2.
[2 mark]
c.
Examiners report
[N/A]
a.
[N/A]
b.
[N/A]
c.
Syllabus sections
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