What is an example from the animal world were a living system is sensitivity into a weak field

the sugar-phosphate backbone forms the structural framework of nucleic acids, including dna and rna. this backbone is composed of alternating sugar and phosphate groups, and defines directionality of the molecule.

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