10 4 A scientist investigated the effect of temperature on the time it takes for blood to clot. The graph shows the results of this investigation. 180 160 140 120 100 80 60 40 20 0 30 32 34 36 38 40 Temperature / °C Clotting time / s (a) Explain how these results show that enzymes are involved in blood clotting. (3) .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... 11 Turn over (b) Prothrombin is involved in the blood clotting process. The F2 gene codes for the synthesis of prothrombin. This gene is located from base pair 46 719 191 to base pair 46 739 504 on chromosome 11. Determine the number of codons in this gene. (1) Answer .............................................................. (c) A mutation of the F2 gene causes thrombophilia, a condition that results in the production of excess prothrombin. In this gene mutation, guanine is replaced with adenine. (i) Name this type of mutation. (1) .................................................................................................................................................................................................................................................................................... (ii) People without this mutation have a 1 in 1000 risk of producing a blood clot in an artery. The mutation increases this risk by 20 times. State the probability of producing a blood clot for people with this mutation. (1) .................................................................................................................................................................................................................................................................................... (iii) Explain why thrombophilia increases the risk of producing a blood clot in an artery. (3) .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... 12 (d) A genetic test can be used to find out if a person has thrombophilia. The test involves using a restriction endonuclease to obtain genetic material from white blood cells. This genetic material is then used in the polymerase chain reaction (PCR). (i) State the role of a restriction endonuclease. (1) .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... (ii) Describe the process of PCR. (3) .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... (Total for Question 4 = 13 marks)