Final answer:
The frontal (coronal) plane would not show the lungs in both sections when cutting a dissection animal, as it divides the body into front and back portions, unlike the sagittal and transverse planes.
Step-by-step explanation:
The body plane that would not show the lungs in both sections when a dissection animal is cut along two planes is the frontal (or coronal) plane. This plane divides the body into an anterior (front) portion and a posterior (back) portion, which would not allow both lungs to be visible in each section, as the lungs are situated side by side in the chest cavity. In contrast, the sagittal plane divides the body into right and left portions, and the transverse plane divides the body horizontally into upper and lower portions, both of which would show the lungs in each section.