Izzy sees a leopard in her backyard. her pupils are dilated and her heart is pounding; her breathing is shallow and rapid. her nervous system is active.

Izzy's sympathetic nervous system is active. This part of the nervous system is responsible for the fight or flight response of the body. Also, it helps the body to maintain homeostasis. The two types of neurons present in this system that is responsible for any transmission of signals are the pre ganglionic and post-ganglionic. 

The answer is atmosphere. there are four spheres of the earth: 1. geosphere (from greek word 'geo' = ground), 2. hydrosphere (from greek word 'hydro' = water), 3. biosphere (from greek word 'bio' = life), and 4. atmosphere (from greek word 'atmo' = air). a magnetosphere is a region of space around astronomical objects controlled by the magnetic field of that object. through the process of elimination, since lightning is present in the air, it can be found in the atmosphere.