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Date November 2018 Marks available 3 Reference code 18N.3.HL.TZ0.11
Level Higher level Paper Paper 3 Time zone TZ0 / no time zone
Command term Explain Question number 11 Adapted from N/A

Question

Golden rice (Oryza sativa, GR) is the generic name given to genetically modified rice that produces beta-carotene (provitamin A). Golden rice was created by transforming rice with the gene coding for the PSY protein (phytoene synthase) from daffodil (Narcissus pseudonarcissus) or from corn (Zea mays).

The picture shows variations of rice.

A   White wild-type rice

B   Yellow Golden rice expressing the gene coding for PSY from daffodil

C   Orange Golden rice expressing the gene coding for PSY from corn

[Reprinted from TRENDS in Plant Science, 10(12), S. Al-Babili and P. Beyer, 'Golden Rice – five years on the road – five years to go?',
pp. 565--573, Copyright (2005), with permission from Elsevier. https://www.sciencedirect.com/journal/trends-in-plant-science]

Outline how scientists would determine whether the gene coding for PSY from daffodils has been taken up successfully by rice DNA.

[1]
a.

Discuss whether production of Golden rice is an example of biopharming.

[2]
b.

Agrobacterium tumefaciens was used in the production of Golden rice varieties. Explain how this bacterium is used to produce genetically modified crop plants.

[3]
c.

A bioinformatics analysis was performed on the protein PSY transcribed from the gene from corn and from daffodil to obtain the sequence alignment.

On the alignment, identify the longest part of the sequence where the consecutive amino acids are the same.

[1]
d.

BLASTp was used to obtain the alignment of the genes coding for PSY. Outline reasons for BLASTn not being suitable for obtaining this alignment.

[2]
e.

In the alignment there are dashes (–) in some positions. Deduce what is indicated by these dashes.

[3]
f.

Markscheme

a. by detecting a marker/resistance/sequencing gene ✔
Accept PCR to detect the marker gene.

b. the offspring produce yellow rice ✔

a.

a. biopharming is the introduction of genes into another species for medical use ✔

b. β-carotene/provitamin A is added to rice to prevent «night» blindness/diseases ✔

c. through genetic engineering ✔

b.

a. «Ti/tumour inducing» plasmid of A. tumefaciens/bacterium causes tumours/galls ✔

b. Ti incorporates genes «of β-carotene synthesis»
OR
Ti is used as a vector of the gene «for β-carotene» ✔

c. recombinant plasmids reintroduced into A. tumefaciens/bacterial cells ✔

d. bacteria infect rice plant cells ✔

e. the newly incorporated gene produces β-carotene/Golden Rice ✔

c.

sequence shown on alignment:

d.

a. BLASTp aligns amino acids «of proteins» ✔

b. BLASTn aligns nucleotides «of DNA/RNA» ✔

c. amino acid sequence is shown therefore BLASTn would not work ✔

e.

a. dashes are shown where there is no alignment ✔

b. due to lack of amino acids on one of the sequences ✔

c. in order to make them align the computer introduces gaps ✔

d. the sequence with dashes does not include the sequence of the other protein shown ✔

f.

Examiners report

[N/A]
a.
[N/A]
b.
[N/A]
c.
[N/A]
d.
[N/A]
e.
[N/A]
f.

Syllabus sections

Option B: Biotechnology and bioinformatics » Option B: Biotechnology and bioinformatics (Core topics) » B.2 Biotechnology in agriculture
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Option B: Biotechnology and bioinformatics » Option B: Biotechnology and bioinformatics (Core topics)
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