According to the fossil record, when did the dinosaurs become extinct?
a
at the start of the mesozoic era
b
at the start of the paleozoic era
c
at the end of the mesozoic era
d
at the end of the paleozoic era

the endocrine system secretes hormones into blood and other body fluids. these chemicals are important for metabolism, growth, water and mineral balance, and the response to stress. hormones provide feedback to the brain to affect neural processing. reproductive hormones affect the development of the nervous system.

b. heterotroph

explanation: