The dramatic tone of the novel is seen though the chapters in which the selling of slaves is depicted.The type of transaction required is sad in the sense that the author uses a part of the history of the US when black people were treated as property- because they were by law.Mr Haley is a very ruthless slave trader as we can read in chapter one . Tom is religious and beleives in God.What could provide a comic tone in between the horros of slavery are most of his sermons or the sermons by the Quackers in order to show that even in the worst situations God is with us.
The story in itself is not funny .However, the narrator plays a little with the situations presented in the story as a result of the slave trade by the time .In doing so , the author is a little ironic and the irony, for example in Tom´s attitudes and decision not to bertray whom he loves, is meant to leave a moral about the destructive effects of slavery.
I will provide some main ideas for you to write the 150-word essay.
It might be said that it is the narrator who tried to "educate" the reader about slavery. he did it through moral conclusions and comments. These might give a serious and dramatic tone to the story. Through his narrations, the reader gets to know the characters and their actions. he also speaks directly to the audience in his own voice, he is angry, amused,sarcatic, etc. His changes would affect the tone of the story.