1. 1
   A biotechnology company wants to make cotton plants resistant to attack by caterpillars. Scientists identify a gene from the bacterium Bacillus thuringiensis that codes for a protein toxic to caterpillars but harmless to humans. They plan to cut this gene out of the bacterial DNA and insert it into the DNA of cotton plant cells, then grow whole GM cotton plants from the modified cells.

   (a)

   Which enzyme is used to cut the desired gene out of the bacterial DNA at a specific sequence?

   [1 mark]

   • ARestriction enzyme
   • BLigase
   • CAmylase
   • DDNA polymerase

   (b)

   Cutting the gene with a restriction enzyme leaves single-stranded, unpaired sections of DNA at each end of the cut fragment. What are these unpaired sections called?

   [1 mark]

   • AVectors
   • BSticky ends
   • CPlasmids
   • DChromosomes

   (c)

   Describe how the gene, once cut out, is inserted into the DNA of a cotton plant cell so that the cell will produce the toxin protein.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   A banana plantation loses a valuable variety of banana to a fungal disease. Only one healthy plant of this variety survives. To rapidly produce thousands of genetically identical, disease-free plants from small pieces of tissue taken from the surviving plant, growers use a laboratory technique in which cells are grown on a nutrient gel containing plant hormones until they develop into complete new plants.

   (a)

   What is this technique called?

   [1 mark]

   • AGenetic engineering
   • BSelective breeding
   • CTissue culture
   • DNatural selection

   (b)

   Because every plant produced by this technique is genetically identical to the surviving plant, what term describes the group of plants produced?

   [1 mark]

   • AA clone
   • BA hybrid
   • CA mutant strain
   • DA cross-breed

   (c)

   Explain one advantage of using tissue culture, rather than growing new plants from seed, to preserve this banana variety.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A dairy farmer wants to increase the average milk yield of her herd. Each year she identifies the cows that produce the most milk and breeds only from these cows and from bulls whose mothers had high milk yields. She repeats this process over many generations.

   (a)

   Describe the process the farmer is using and explain why the average milk yield of the herd increases over successive generations.

   [3 marks]

   (b)

   After many generations of this selective breeding programme, explain one disadvantage that the farmer might notice in her herd, and suggest how she could reduce this risk.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A government agency in a country prone to drought is deciding how to develop a new variety of maize that can survive with much less water. Two proposals are put forward: Proposal 1 is to use genetic engineering to insert a drought-tolerance gene taken from a desert-adapted grass species directly into maize DNA. Proposal 2 is to use selective breeding, repeatedly cross-pollinating existing maize varieties that already show some natural drought tolerance and selecting the most tolerant offspring over many generations.

   (a)

   Evaluate the practical and ethical implications of using genetic engineering (Proposal 1) to produce this drought-tolerant maize.

   [6 marks]

   (b)

   Evaluate the practical and ethical implications of using selective breeding (Proposal 2) instead to produce this drought-tolerant maize, and suggest which proposal the agency should choose, giving a reason.

   [6 marks]

   Total for question 4: 12 marks

End of questions