CloningIB MYP Biology: Subtopic test

1. 1
   A tea farm in Kenya has one bush that produces an exceptionally high yield of leaves with a strong flavour. The farm manager cuts short stems from this bush, dips them in rooting powder and plants them in a nursery bed. After a few weeks the stems grow roots and become new bushes.

   (a)

   What is a clone?

   [1 mark]

   • AAn organism produced by mixing the genes of two parents
   • BAn organism that is genetically identical to its parent
   • CAn organism whose genes have been changed in a laboratory
   • DAn organism that is bigger than its parent

   (b)

   Which type of cell division produces the new cells that grow into a bush from a cutting?

   [1 mark]

   • AMeiosis
   • BFertilisation
   • CDiffusion
   • DMitosis

   (c)

   Explain why the new bushes grown from the cuttings have the same characteristics as the original bush.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   In 1996 scientists in Scotland produced Dolly the sheep. They removed the nucleus from an unfertilised egg cell taken from Sheep 1 and replaced it with the nucleus from an udder cell taken from Sheep 2. A small electric pulse made the cell start to divide, and the resulting embryo was placed in the uterus of Sheep 3, who gave birth to Dolly.

   (a)

   Why did the scientists remove the nucleus from the egg cell?

   [1 mark]

   • ASo that the embryo's genes would come only from the udder cell nucleus
   • BSo that the egg cell could be fertilised by a sperm
   • CSo that the egg cell would stop respiring
   • DSo that the embryo would have no DNA at all

   (b)

   Which sheep was Dolly genetically identical to?

   [1 mark]

   • ASheep 1, the egg cell donor
   • BSheep 3, the sheep that gave birth to her
   • CSheep 2, the udder cell donor
   • DNone of them, because all her genes were new

   (c)

   Dolly looked like Sheep 2, not like Sheep 3, who gave birth to her. Explain why.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A biotechnology company grows orchids by tissue culture. Small pieces of tissue from one orchid are placed on sterile jelly containing nutrients and rooting hormone. In a trial, the company used 10 pieces of tissue at each of four hormone concentrations (0, 1, 2 and 3 mg per litre), kept all of them at 22 °C in the light for six weeks, and counted the roots on each plantlet. The mean number of roots per plantlet was 1.2, 3.8, 6.1 and 6.3 respectively.

   (a)

   Identify the independent variable, the dependent variable and one control variable in this trial.

   [3 marks]

   (b)

   Describe the trend in the results and suggest, with a reason, which hormone concentration the company should use.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A dairy farm in the Netherlands wants to use adult cell nuclear transfer to produce copies of its best cow, which gives 12 000 litres of milk a year. Cloning costs thousands of euros for each calf, and many of the embryos fail to develop into healthy calves. The farm currently improves its herd by selective breeding, which takes many generations.

   (a)

   Discuss the benefits and drawbacks of cloning the cow, and conclude whether the farm should go ahead.

   [6 marks]

   (b)

   Evaluate the statement: 'Cloning is a better way than selective breeding for the farm to improve its herd.'

   [6 marks]

   Total for question 4: 12 marks

End of questions