<p>From what I know, CS majors can take either course. Which one did you take?</p>
<p>Not all CS degree programs require science (other than CS and math) beyond general breadth requirements.</p>
<p>Neither chemistry nor biology is specifically useful for CS, unless you end up doing CS work where chemistry or biology is the application. Physics may be more useful if you do things closer to the hardware.</p>
<p>Depending upon the school you may be required to take chemistry and physics with biology as optional science elective. The science sequences are designed for you to have a comprehensive education. As ubalumnus noted, neither chemistry nor biology has specific applications in CS so you might as well chose whichever you think will be more interesting.</p>