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Date November 2018 Marks available 2 Reference code 18N.2.HL.TZ0.3
Level Higher level Paper Paper 2 Time zone TZ0 / no time zone
Command term State Question number 3 Adapted from N/A

Question

State one similarity and one difference between the structure of genes and short tandem repeats.

[2]
a.

Outline the role of short tandem repeats in DNA profiling.

[2]
b.

Markscheme

similarity:

both made of DNA/nucleotides
OR
both have bases/adenine/cytosine/guanine/thymine
OR
neither has uracil ✔

 

difference

genes are longer/have longer DNA/base sequences «without repeats»
OR
genes have introns/exons but tandem repeats do not
OR
genes have base sequences that code for polypeptides/proteins and tandem repeats do not ✔

a.

a. tandem repeats allow individuals to be distinguished/compared/identified
OR
tandem repeats are used to identify the source of a DNA sample ✔

b. unique/different number of repeats/combination of tandem repeats in each individual
OR
unique/different pattern of bands in each individual ✔

c. PCR used for copying/amplifying «tandem repeats» ✔

d. gel electrophoresis used for separation «of tandem repeats»/create pattern of bands ✔

b.

Examiners report

[N/A]
a.
[N/A]
b.

Syllabus sections

Additional higher level » Topic 7: Nucleic acids » 7.1 DNA structure and replication
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Additional higher level » Topic 7: Nucleic acids
Additional higher level

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