Advanced task killer on android help?

Okay so I have the LG Apex, its an android powered phone. I got the advanced task killer application because when we went to go get my brothers phone (my whole family has the same one) my mom asked why the battery life was so bad on the android. He said its because the smartphones run/do more stuff than a regular phone does, therefor it uses more battery, so he told us to get the advanced task killer. I have this, but when I go into it every once in a while to kill applications, I have numerous applications that I never even opened or have to do with anything I have opened in any way. For example, I killed the apps, then all I was doing was texting my friend, then I go back in a little bit later (still haven't done anything else except text) and I have a whole bunch on the list, like voice search, calendar, alarm clock, ect. Has anyone else encountered this problem? And do you know why it does this? Thanks soo much!