In this animated object, students observe how ATP energy is used to move substances across the cell membrane from an area of lower concentration to an area of higher concentration and when something too large needs to get in or out of a cell.

In this interactive exercise, learners review definitions of 26 terms and then test their knowledge in a matching exercise. Only six terms are included in the quiz; however, if the learner clicks “Restart,” more terms appear in random order.

In this animated activity, learners examine the conductivity of a solution and how its properties affect measurements to determine concentration levels. A brief quiz completes the learning object.