page 11 26. Pramipexole is a drug used to treat the symptoms of Parkinson’s disease. Pramipexole acts like a natural compound in the body, dopamine, to stimulate nerve cells. Buprenorphine is a drug used to treat heroin addiction. Buprenorphine stimulates receptors in the body but produces less of a response compared to heroin. Which line in the table best describes pramipexole and buprenorphine? Pramipexole Buprenorphine A agonist agonist B agonist antagonist C antagonist agonist D antagonist antagonist 27. The human nose can generally detect the toxic gas hydrogen sulfide at levels of 0·03 ppm. If a person inhales 6 litres of air per minute, containing 0·03 ppm of hydrogen sulphide, what mass of hydrogen sulfide is inhaled in 10 minutes? A 2 g B 1·8 g C 200 mg D 1·8 mg 28. Which of the following techniques could be used to purify an impure sample of solid caffeine? A Thin layer chromatography B Heating under reflux C Recrystallisation D Distillation [Turn over