Date | November 2018 | Marks available | 1 | Reference code | 18N.3.sl.TZ0.8 |
Level | SL | Paper | 3 | Time zone | TZ0 |
Command term | Name | Question number | 8 | Adapted from | N/A |
Question
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.
Name the type of link between the two monosaccharide residues.
[1]
a.
Outline how the two monomer structures, galactose and glucose, differ.
[1]
b.
Markscheme
«1,4-»glycosidic ✔
Do not accept “glucosidic”.
a.
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.
b.
Examiners report
[N/A]
a.
[N/A]
b.