Answer
Reductionism is necessary because it helps us to track down the problem by breaking down the fundamental structures into smaller pieces and understand what is happening at a specific level, but it is not sufficient to diagnose a patient because the body is one organism and all systems and cells work together. Because of this, understanding one part or level will not be sufficient to diagnose a patient as they are all connected.
Work Step by Step
I used my own logic and understanding of anatomy on this question. If we look at a patient for example, when one organ shuts down or begins to fail, many organs are affected. If one cell is affected it could spell disaster for the whole organism.Your body is a house of cards and if even one falls it could affect many other parts. Also pg 14 helps on this question