Biology is incomparable to computers, or to any other man-made machine. In computers the components interact in well-defined separable and independent roles. In a biological organism, all components depend heavily on not just one or two other components, but many. The role we impute for each mechanism often interfere and/or collaborate with other seemingly unrelated mechanisms, often in hierarchical and nonlinear fashion. That's why the function of even simple biological subsystems is so challenging to decipher. Context and interdependency are everywhere. That's why the oxymoronicism of a biologist “fixing a radio” rings so true.
Very much applicable to software as well :-) Modern systems are so complex there're very few people (if at all) who understand everything in them, even though they were man-made over time.
