Exposition refers to the beginning of a story, where the author establishes a setting, introduces the characters, and provides a foundation for all of the coming action and conflict. We get to know the characters a little bit, and are given pertinent background information that will help us to understand their reactions in the face of the succeeding plotline. Given that definition, the exposition in "Life of Pi" is quite a long one, about 1/3 of the entire book. It is when Pi and his family are in India. We learn about Pi, his life, his family, and then, are given a lot of very important information on zoology and religions, that play a crucial role in the coming story, and in the ending of the tale. We learn all about animals, boundaries, training, zoos, respect and safety--all of these things play a role in the lifeboat. We learn of Pi's devotion to three different religions, and how he felt that each of them had really great stories, so loved all of them. That will tie in directly to the ending.
Rising action occurs with the introduction of the conflict during the shipwreck, and all of the struggles that Pi has trying to survive. There are various different points that could be considered the climax--this novel is a bit unique in the fact that so many difficult struggles are had in his journey that each one is intense and potentially life-changing. However, when we don't know if Pi is going to make it through, when his eyesight is gone, and all hope seems to be lost--that is one potential climax point that brings all of the action to a head.
The resolution, where the main conflict is resolved and things are smoothing out, occurs when he does survive, and finally reaches land and recovers from his journey. He is interviewed by the Japanese men, and tells his story. I hope that helps; good luck!