DP Chemistry (last assessment 2024)

Test builder »

Question 23M.3.HL.TZ2.14

Select a Test
Date May 2023 Marks available [Maximum mark: 3] Reference code 23M.3.HL.TZ2.14
Level HL Paper 3 Time zone TZ2
Command term Identify, Outline Question number 14 Adapted from N/A
14.
[Maximum mark: 3]
23M.3.HL.TZ2.14

Monosaccharides combine to form polymers.

(a)

Identify one similarity and one difference between the structures of starch and cellulose.


Similarity: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

 

Difference: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

[2]

Markscheme

Similarity:
polymers of glucose
OR
«1-4» glycosidic «links» ✓

Difference:
starch contains α-glucose AND cellulose contains β-glucose
OR
starch contains α AND cellulose contains β «1-4» glycosidic links
OR
starch «may contain» 1-6 glycosidic links AND cellulose does not
OR
starch «may be» branched AND cellulose unbranched ✓

 

Do not accept “both are polysaccharides” for M1.
Accept alpha or beta for symbols in M2.

(b)

Outline why humans cannot digest cellulose.

[1]

Markscheme

lack of cellulase/enzyme ✓