<span>a. chemicals produced by neurons that function as hormones—neurohormones
b. chemicals that act locally on nearby cells—paracrine factors
c. chemicals secreted by presynaptic terminal—neurotransmiters
d. influences same cell type from which it is secreted—autocrine agent
e. chemical secreted into the blood by specialized cells; travels some distance to target tissues—endocrine hormones</span>
Answer: The carbon cycle helps regulate Earth's temperature.
C 3; 1 3 to 1 im a fly exp
