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Date November 2019 Marks available 3 Reference code 19N.3.SL.TZ0.9
Level Standard level Paper Paper 3 Time zone TZ0 / no time zone
Command term Outline Question number 9 Adapted from N/A

Question

A study was carried out in Brazil on the transfer of pollen (cross-pollination) from transgenic strains to non-transgenic strains of soybean (Glycine max). The transgenic crop was resistant to the herbicide glyphosate. The graph below shows the percentage of cross-pollination between transgenic and non-transgenic crops in fields separated by different distances.

[Source: S Abud, et al., (2007), Gene flow from transgenic to nontransgenic soybean plants in the Cerrado region of Brazil,
Genetics and Molecular Research, 6 (2), pages 445–452]

Suggest one undesirable consequence of cross-pollination involving glyphosate resistant crop plants with other plants.

[1]
a.

Using the data, suggest one recommendation to farmers who plant transgenic soybeans.

[1]
b.

Agrobacterium tumefaciens stains pink or red with the Gram stain. Deduce from this result what type of bacterium A. tumefaciens is.

[1]
c.

Outline how A. tumefaciens is used to introduce genes into soybeans.

[3]
d.

Markscheme

transfer of resistance genes to non-transgenic/organic crops
OR
transfer of resistance genes to wild relatives/development of weed resistance ✔

a.

separate fields by at least 5m because at this distance no cross pollination occurs ✔

Needs a reason.

b.

«Gram» negative ✔

c.

a. genes to be transferred are introduced into a tumour-inducing/Ti plasmid/vector ✔

b. ‹embryo, seedling leaf› tissue is damaged/wounded / callus formed ✔

c. A. tumefaciens recognizes/is chemically attracted to damaged/wounded tissue ✔

d. A. tumefaciens transfers tumour-inducing/Ti plasmid/vector into plant cell ✔

e. plasmid integrates into plant cell genome ✔

d.

Examiners report

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

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)
Option B: Biotechnology and bioinformatics

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