Answer:
d. endocytosis and exocytosis
Explanation:
oxygen has 8 protons and 8 electrons. In order to get the number of neutrons you take the atomic weight in this case 15.9999~16 and you subtract it by the number of protons (16-8).
The circulatory system is responsible for moving blood cells throughout the body.
Answer:
Arthropods have a tough, non-living outer shell called exoskeleton, which protect their soft bodies while echinoderms have living endoskeletons, which develops within the deeper skin or body tissues and act as their protective covering.Explanation: