How about seeing some real cells in action? Here is a Trachelius ciliate feeding on a Campanella ciliate, and here is a Paramecium feeding:
For self-assessment questions, with exercises and discussions, just click on the correct topic at Biology GCSE & IGCSE Question Bank. Powerpoints can be downloaded from the same site here. The s-cool revision site lets you revise the topic, summarizes the topic & tests you on it. Skoool gives you a lesson, including progress questions, for each Biology topic but you’ll need sound on for it.
Just click to enlarge (thank you LadyofHats).