when you breathe in air you bring oxygen into your lungs and blow out. A. Carbon dioxide B. oxygen C. carbon monoxide D. hydrogen

The first signs of cellular differentiation occur in the blastocyst. why is cellular differentiation important for the development of a fully formed human infant?

Which entry is in the wrong position in the table?

Which of the following statements about archaea and bacteria is true? a. neither is single-celled. b. they both have nuclear membranes. c. neither reproduces by binary fission. d. they both lack a nuclear membrane.