Here are three apps that will help your students get a better understanding of some biology basics. Each app allows the user to explore the topic with detailed, interactive graphics. Best of all each app is free!
HudsonAlpha iCell (Free, available for both Android (https://play.google.com/store/apps/details?id=org.hudsonalpha.icell&feature=search_result and iOS devices https://itunes.apple.com/us/app/hudsonalpha-icell/id364882015?mt=8 ) This app allows the user to explore the cells of animals, plants and bacteria. Each simulation allows the user to zoom in and rotate the cell. Each part is labeled and explained. There are three levels of explanation, basic, intermediate and advanced. There is also a website that has the same content: http://www.hudsonalpha.org/education/digitaleducation/icell
Virtual Heart (Free, available for the iPad, iOS 4.0 and later https://itunes.apple.com/us/app/virtual-heart/id501539525?mt=8 ) This app explores the human heart. It offers interior and exterior views of the beating heart. The view can be changed by swiping up and down. You can also change the heart rate with a simple up and down arrow. Labels can be turned on and off. You can also look at the electrical system, valves and blood flow. All of this with an easy to use interface. Unfortunately you cannot rotate the heart to see it at multiple angles, although with all the other details included, this isn’t that much of an issue.
Anatomy 4D (Free, available for iOS https://itunes.apple.com/us/app/anatomy-4d/id555741707?mt=8 and Android devices https://play.google.com/store/apps/details?id=com.daqri.d4DAnatomy&hl=en ) This app is different because it uses Augmented Reality to display the human body. To use it you need to first print out the marker which tells the device what to display. From there you can see the human body in many levels of detail. Skin visibility is controlled with a slider that ranges from completely visible (nude) to no skin shown. Both male and female models are included. Systems include: muscular, skeletal, circulatory, nervous, gastrointestinal, respiratory, reproductive, urinary and lymphatic. Unfortunately no labels are included. As a teacher you have to decide, based on your classroom, school and community), how to use this app. One good use may be to use it as a teacher tool with very limited student interactivity.