Biology 9700 · AS & A Level · Genetically modified organisms in agriculture
Genetically modified organisms in agriculture — practice question
There are numerous strains of the soil bacterium $Bacillus\ thuringiensis$. Each strain makes slightly different Cry-proteins, and these are poisonous to insects. Some varieties of cotton, called Bt cotton, have been genetically altered so that they make one of these proteins, Cry1Ac. This protein is especially effective at killing the larvae of butterflies and moths, including the cotton bollworm, $Helicoverpa\ zea$, which is a major pest of cotton crops.
The genetically modified cotton includes a ‘genetic package’ containing:
• the gene for Cry1Ac, the Bt protein
• promoter sequence
• a herbicide resistance gene used as a marker.
(a(i))[2]
Suggest the advantages of using, in Bt cotton, the gene for Cry1Ac rather than one of the genes for other types of Cry-protein.
(a(ii))[2]
Explain why a promoter is included in the genetic package.
(a(iii))[3]
Suggest how the herbicide resistance gene can be used as a genetic marker.
(b(i))[2]
With reference to Table 4.1, compare the expenses involved in growing Bt cotton with the expenses involved in growing non-GM cotton.
(b(ii))[1]
Table 4.1 shows that farmers who grow Bt cotton have a higher net income than those who grow non-GM cotton. Use the information in the table to suggest one reason why some farmers in India choose to grow non-GM cotton instead of Bt cotton.
(c)[3]
In one region of India, Andhra Pradesh, a severe drought in 2002-2003 meant that Bt cotton performed less well than other cotton varieties that were better suited to the conditions. Suggest how a variety of Bt cotton that is better adapted to dry conditions could be produced from the existing varieties of Bt cotton, without using gene technology.
Worked solution & mark scheme
This 13-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Targets only particular insect pests” …