DP Chemistry (last assessment 2024)
Question 18M.3.sl.TZ2.7
| Date | May 2018 | Marks available | [Maximum mark: 5] | Reference code | 18M.3.sl.TZ2.7 |
| Level | sl | Paper | 3 | Time zone | TZ2 |
| Command term | Deduce, Draw, Outline | Question number | 7 | Adapted from | N/A |
7.
[Maximum mark: 5]
18M.3.sl.TZ2.7
Amino acids are the building blocks of proteins.
(a)
Draw the dipeptide represented by the formula Ala-Gly using section 33 of the data booklet.
[2]
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]
(b)
Deduce the number of 1H NMR signals produced by the zwitterion form of alanine.
[1]
Markscheme
3
[1 mark]
(c)
Outline why amino acids have high melting points.
[2]
Markscheme
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]