Genome mapping and DNA technologyIB MYP Biology: Subtopic test

1. 1
   The Human Genome Project was an international research programme in which scientists from several countries worked together between 1990 and 2003 to find the order of the bases in human DNA. It showed that humans have about 20 000 genes, and the results were made available free to researchers around the world.

   (a)

   What is meant by the genome of an organism?

   [1 mark]

   • AThe number of chromosomes in each gamete
   • BA single gene that codes for one protein
   • CThe proteins found in all the body cells
   • DThe complete set of genetic material (DNA) of the organism

   (b)

   What did the scientists determine when they sequenced the human genome?

   [1 mark]

   • AThe shape of every human protein
   • BThe mass of the DNA in one cell
   • CThe order of the bases in human DNA
   • DThe number of cells in the human body

   (c)

   Outline two ways in which knowing the sequence of the human genome can help medicine.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   Police in Dubai find blood on a window at the scene of a burglary. A forensic scientist extracts DNA from the blood, cuts it into fragments with enzymes and separates the fragments by size using gel electrophoresis. This produces a pattern of bands, called a DNA profile. The profile is compared with profiles from two suspects. The bands of Suspect 1 match the pattern from the blood, but the bands of Suspect 2 do not.

   (a)

   Why can DNA profiling be used to identify a person?

   [1 mark]

   • AEvery person has exactly the same DNA, so the pattern is easy to compare
   • BApart from identical twins, every person has a unique DNA pattern
   • CDNA changes from day to day, so it shows when the blood was left
   • DOnly criminals have DNA in their blood

   (b)

   Which conclusion can be drawn from the results about Suspect 2?

   [1 mark]

   • AThe blood did not come from Suspect 2
   • BSuspect 2 was never at the scene
   • CSuspect 1 definitely committed the burglary
   • DSuspect 1 and Suspect 2 are related

   (c)

   Explain why the DNA match does not prove that Suspect 1 committed the burglary.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A paternity test is carried out on a girl, her mother, and two men (Man A and Man B) who each say they are the girl's father. The girl's DNA profile has six bands. Four of her bands match bands in her mother's profile. The other two bands do not match her mother. Both of these two bands are found in the profile of Man A. Only one of them is found in the profile of Man B.

   (a)

   Describe how these results are used to decide which man is the girl's father.

   [3 marks]

   (b)

   A scientist says the test proves 'beyond doubt' that Man A is the father. Evaluate this statement.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A country is considering a national programme to test every newborn baby's DNA for a serious inherited disorder such as cystic fibrosis, so that treatment can start early. Results would be stored on a national database. Some families would also be offered gene therapy trials, in which working copies of a gene are put into a patient's cells to make up for a faulty allele. Some people worry about who would be able to see the genetic information.

   (a)

   Discuss the benefits and risks of testing every newborn baby's DNA, and give a justified conclusion.

   [6 marks]

   (b)

   Evaluate gene therapy as a way of treating an inherited disorder such as cystic fibrosis.

   [6 marks]

   Total for question 4: 12 marks

End of questions