List the 3 major eras from past to present.

Aflashlight battery is an example of a) potential energy b) kinetic energy c) thermal energy d) solar energy

Blood stem cells may develop into any kind of human blood cells. what kind of stem cells are blood stem cells? a. multipotent stem cells o b. totipotent stem cells o c. pluripotent stem cells o d. unipotent stem cells

Hemoglobin is a proton that carries oxygen around your body what is hemoglobin made from