Does laptop battery last less when I'm charging my Iphone on it?

If the laptop is not connected to a battery plug, and if i'm charging my Iphone on the laptop, will the laptop battery dry up faster? Will the Iphone "suck" battery away from the laptop making discharge faster?

Yes it will, sorry

Of course, you are taking power from laptop battery to charge iPhone battery. Basically, you are moving some of the laptop capacity to the iPhone battery instead.

Of course.mobile battery steal energy from laptop battery.