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.
Explain the role of bioinformatics in the determination of the function of an unknown target gene.
Outline what is meant by open reading frame (ORF).
Genetic engineers sometimes use physical methods to transform cells. Describe the method of biolistics.
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
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
Continuous/unbroken stretch of DNA between start codon and stop codon
Biolistics uses a gun device
Fires particles coated with DNA/gene
At plant tissue
Examiners report
The graph proved quite difficult to interpret as longer bars show less plowing.
Most scored for comparing function of a known sequence with an unknown gene.
N/A
Very few mentioned the use of a gun device in biolistics.