Why did he end the book with a conversation with his mum and why did he add an extra chapter on apartheid?

While Noah has always loved his mother, the prospect of losing her clarifies just how much she means to him. He feels angry and helpless that he couldn't protect her, but he does what he can by paying her medical bills. Noah shows courageous honesty in admitting that he hesitates over the prospect of signing up for a lifetime of debt, but his love for his mother wins out. Patricia's luck—or, as she sees it, her faith—means that a very serious incident results in only minor injuries. Ending the memoir with a joking exchange between mother and son shows that no matter what dark incidents happen to them, they are each other partners in resilience and hope.I think the extra section on apartheid is primarily meant to educate his young reading audience to that type of racial segregation in history.