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Date May 2016 Marks available 2 Reference code 16M.3.SL.TZ0.10
Level Standard level Paper Paper 3 Time zone TZ0
Command term Explain Question number 10 Adapted from N/A

Question

Before planting their crops, farmers have traditionally plowed their land to suppress weed growth. Unfortunately, plowing causes the loss of valuable topsoil. Modern farming is shifting toward the use of chemical weed killers such as glyphosate in combination with genetically modified glyphosate-tolerant (GT) crops. The graph shows the area of plowed land in the USA for soybeans in 1996 and 2001. During that period GT soybean planting increased from a few percent to about 70 %.

Evaluate the hypothesis that increased planting of glyphosate-tolerant crops has resulted in the reduction of plowing.

[2]
a.

Explain the role of bioinformatics in the determination of the function of an unknown target gene.

[2]
b.

Outline what is meant by open reading frame (ORF).

[1]
c.

Genetic engineers sometimes use physical methods to transform cells. Describe the method of biolistics.

[2]
d.

Markscheme

«The hypothesis is supported as» less total land is plowed in 2001

«The hypothesis is supported as» the amount of land used for conventional plowing is less in 2001

«The hypothesis is supported as» the amount of land used for reduced plowing has increased in 2001

There is a negative correlation between increased GT soybean planted and area of land plowed

a.

Involves database search for DNA sequence similar to unknown gene

Function of similar sequence used to infer the function of the unknown target gene

Use of nucleotide blast/BLASTn

b.

Continuous/unbroken stretch of DNA between start codon and stop codon

c.

Biolistics uses a gun device

Fires particles coated with DNA/gene

At plant tissue

d.

Examiners report

The graph proved quite difficult to interpret as longer bars show less plowing.

a.

Most scored for comparing function of a known sequence with an unknown gene.

b.

N/A

c.

Very few mentioned the use of a gun device in biolistics.

d.

Syllabus sections

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