50 points

which system is responsible for the exchange of oxygen and carbon dioxide?

a. skeletal
b. circulatory
c. respiratory
d. endocrine

What are the two main phases of a cell cycle

Explain how the number of similarities between the embryos from early stage to late stage is used as evidence of a common ancestry

Which is a function performed by stem cells in the skin a. replacing lost skin cells b. making cells for the intestines c. growing new organs d. differentiating into brain cells plz apex