Marcus suffers from nicotine addiction. He started smoking cigarettes at the age of 14, and now smokes at least 25 cigarettes every day. If Marcus cannot have a cigarette immediately after waking up, he becomes extremely irritable, suffers from severe headaches, and cannot concentrate on his university lectures. Marcus's father and paternal grandfather were also both heavy smokers who struggled in vain to quit.
Discuss one biological explanation for Marcus's nicotine addiction. You must make reference to the context in your answer.
Practise Edexcel A Level Psychology Content with exam-style questions for A Level Psychology. 1,059 questions covering Issues around drug taking, Biological explanations of drug addiction, Learning explanations of drug addiction, Treatments for drug addiction, Anti-drug campaign and strategies, Individual differences, and Developmental psychology, matched to the Edexcel A Level Psychology (9PS0) specification and written in Paper 1, Paper 2 and Paper 3 style. Every question includes a full worked solution and mark scheme, so you can see where marks are awarded rather than just whether you got the answer right.