Teaching Loads by Field at Research Universities
There is no standard load; it depends widely on the department, the number of students enrolled, the available number of faculty, and so on. 

Moreover, in some departments, it is possible to fundraise your way out of commitments. For instance, if you bring in X dollars in overhead, you can "buy" out of teaching a class for a semester.

In addition, stating that a load is "1-and-1" can mean different things. In the department where I did my graduate work, professors now co-teach one class per semester, and sometimes offer an elective course on top of that 1-and-1 load.