DP Chemistry (last assessment 2024)
Question 18N.3.sl.TZ0.8
| Date | November 2018 | Marks available | [Maximum mark: 2] | Reference code | 18N.3.sl.TZ0.8 |
| Level | sl | Paper | 3 | Time zone | TZ0 |
| Command term | Name, Outline | Question number | 8 | Adapted from | N/A |
8.
[Maximum mark: 2]
18N.3.sl.TZ0.8
Lactose, found in milk and dairy products, is a disaccharide formed from two different monosaccharides. The structure of lactose is shown with numbered carbon atoms.
(a)
Name the type of link between the two monosaccharide residues.
[1]
Markscheme
«1,4-»glycosidic ✔
Do not accept “glucosidic”.
(b)
Outline how the two monomer structures, galactose and glucose, differ.
[1]
Markscheme
H and OH are reversed/in different positions on C-4 ✔
C-4 must be specified.
Do not penalize if reference is made to H and OH above and below ring/in alpha and beta positions on C-4 incorrectly.