A single molecule is the one that is responsible for initiating a signal transduction pathway. The answer in this question is a single molecule. Molecule is defined as an electrically neutral group of two atoms or more held together by a chemical bonds.
Atmospheric Fixation. The enormous energy of lightningbreaks nitrogen molecules and enables their atoms to combine with oxygen in the air forming huge nitrogen oxides. These dissolve in rain, forming nitrates, that are carried to the earth.
CENTRAL NERVOUS SYSTEM INCLUDES THE BRAIN AND SPINAL CORD.
