12. Which is the same for both Sodium and Potassium? a. Number of neutrons
b. Number of valence electrons
c. Number of protons
d. Atomic mass

The nervous system interacts with the endocrine system by a. using hormones as connections b. sending nerve impulses directly to glands c. using neuroendocrine cells as connections d. sending neurotransmitters directly to neurons

Which statement correctly describes other ways in which nebulae and stars are different? a. a star always has a higher density than a nebula. b. stars can form inside a nebula but a nebula can never be produced by any star. c. stars can never form inside a nebula but a nebula can be produced by any star. d. a nebula always has a higher density than a star. reset submit

Which skeletal system is represented by the shaded portion of the skeleton? spongy skeleton compact skeleton axial skeleton appendicular skeleton