Birds are and have a heart.

a. endothermic; three
b. endothermic; four
c. ectothermic; three
d. ectothermic; four

How did the miller-urey experiment impact the way scientists think about the origins of life? use what you know about the miller-urey experiments to discuss the factors needed for life to arise, and speculate on whether life could arise on another planet.

Epinephrine is a hormone released from the adrenal gland of the body, most often in a stressful situation. it is known as the "fight-or-flight" hormone. one way that it causes a response in the body is to activate receptors on muscle cells. where are these cellular receptors located? a. on the cell membrane b. in the nucleus c. on the cell wall d. around the mitochondria

Which must be kept in mind when determining if an explanation is correct? check all that apply.which must be kept in mind when determining if an explanation is correct? check all that apply.