carbon has four valence electrons, so it can achieve a full outer energy level by forming four covalent bonds. this special ability allows carbon to do what?

To form a wide range of compounds with other elements

Explanation:

The ability of carbon to gain four more electrons allows this chemical specie to form a wide range of compounds.

When carbon gains four electrons, it becomes isoelectronic with neon and then becomes a stable compound or molecule as it combines with other atoms.

This leads to the proliferation of carbon compounds that we find in nature. Carbon can easily for covalent compounds with other compounds also.

endo:

regulates body hormones, aldosterone, vasopressin

neural:

signal, regulates body using electric signals, reflex

endo has to do with hormones; aldosterone and vasopressin are both hormones. i also had this question and got it right : d

only about ten percent of the energy at one trophic level is passed on to organisms at the next trophic level. the remainder of the energy is used in life processes or lost as heat.