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Date May 2018 Marks available 1 Reference code 18M.2.HL.TZ2.2
Level Higher level Paper Paper 2 Time zone Time zone 2
Command term State Question number 2 Adapted from N/A

Question

State one role of nucleosomes in eukaryotic cells.

[1]
b.i.

Outline how Hershey and Chase’s experiment provided evidence for DNA as the genetic material.

[3]
b.ii.

State one function for a region of DNA that does not code for proteins.

[1]
b.iii.

Outline the role of the A-site of ribosomes in translation.

[1]
c.i.

Outline the role of tRNA activating enzymes in translation.

[2]
c.ii.

Markscheme

a. help to supercoil/pack DNA in chromosomes 

b. help to regulate transcription / gene expression

b.i.

a. experiment is meant to determine whether DNA or protein is the genetic material 

b. viruses/bacteriophages grown in radioactive S/S35 which enters the protein coat 

c. viruses/bacteriophages grown in radioactive P/P32 which enters the DNA 

d. «radioactive» viral DNA entered the bacterial cell during infection
OR
«radioactive» viral protein did not enter the bacterial cell during infection

b.ii.

regulator of gene expression/introns/telomeres/genes for tRNA / rRNA / promoter / enhancer / silencer / site for primer to bind / codes for mRNA primer

b.iii.

binding/entry of tRNA carrying amino acids/aminoacyl tRNA / charged tRNA / site of transfer of growing polypeptide chains/peptide bond formation

Marks can be awarded to an annotated diagram.

c.i.

a. ATP «hydrolysis» provides energy for amino acid attachment ✔

b. they attach a specific amino acid to the (3') end / free CCA of a tRNA ✔

c. they do this repeatedly / they attach amino acid to all of the tRNA molecules that have anticodon corresponding to that amino acid

c.ii.

Examiners report

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

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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