Many Biology courses for non-majors and many of the texts for such courses tend to be watered down versions of both the majors' courses and texts.  The students are told about cell structure, memorize the equations for photosynthesis or respiration, and study an array of other core topics without knowing enough biology or chemistry to make sense of any of it.  More importantly, the students do not make any connections between what they study in class and anything that is relevant to their lives.  As a consequence, the students hate the experience and leave knowing no more about science than when they arrived, but certain that it is out of their reach and not of their concern.  The problem is exacerbated by the fact that the teachers assigned to the course are often either the least experienced or least interested in teaching it.  The net result is a group of people, none of whom want to be there, thrust together for a semester that causes students to be alienated from science for the rest of their lives.