1. hydrosphere: the system that contains all forms of water; liquid, solid and gas
2. biosphere: the sphere that contains all living things
3. atmosphere: the system that contains the gaseous layer of a planet
4. cryosphere: the system that contain the frozen ice portion of a planet
5. lithosphere: the system that contains the solid rocky crustal portion
In a centrifuged sample of blood the PLATELETS should not be in the plasma portion of the sample. Centrifugation of blood samples separates the blood to its constituents on the basis of their densities. Platelets will be found on the middle region of the separation and not in the upper region where plasma is .
D) the presence of a true nucleus