In autotrophic bacteria, where are chlorophyll like pigments located?

How can antibodies "remember" a particular bacterial invader or "antigen" on that invader?

Some tools have graduations to show multiple measurements. for example, a ruler may have graduations for both millimeters and centimeters. when measuring the length of an earthworm, which graduations would allow for the most accurate measurement? millimeters centimeters decimeters meters

Which skeletal system is represented by the shaded portion of the skeleton? spongy skeleton compact skeleton axial skeleton appendicular skeleton