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Date May 2018 Marks available 2 Reference code 18M.2.SL.TZ1.2
Level Standard level Paper Paper 2 Time zone Time zone 1
Command term State Question number 2 Adapted from N/A

Question

Distinguish between the structure of amylose and the structure of amylopectin.

[1]
a.i.

Suggest the reason for cellulose passing undigested through the human gut.

[1]
a.ii.

Draw an annotated diagram to show how a peptide bond is formed.

[3]
b.

State two structural features that differ between RNA and DNA.

[2]
c.

Markscheme

amylose unbranched/helical while amylopectin branched / vice versa

a.i.

enzymes required to digest cellulose not present in the human gut OWTTE
OR
undigested cellulose provides bulk/fibre

a.ii.

a. correct structure of two amino acids 

b. H2O lost 

c. C from COOH of one links to N of NH2/NH3+ from the other 

d. correct labelling of the peptide bond

e.g.

b.

a. number of strands
OR
(usually) only one strand in RNA/two strands in DNA 

b. base composition
OR
uracil only in RNA / thymine only in DNA 

c. type of pentose
OR
ribose only in RNA / deoxyribose only in DNA

c.

Examiners report

[N/A]
a.i.
[N/A]
a.ii.
[N/A]
b.
[N/A]
c.

Syllabus sections

Core » Topic 2: Molecular biology » 2.6 Structure of DNA and RNA
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Core » Topic 2: Molecular biology
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