The enzymes pepsin and trypsin don't work at the phs of what?

Pepsin works best at about 1 or 2 (it's something like 1.5), and trypsin works best at about 8 to 9 (about 8.7). Although it can vary slightly.

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.

Confused on question what should we be answering