During which stage of fetal development do the heart and lungs of a fetus become fully developed and functional?

If scientists are wrong about earth's age based on radioactive material and the decay rates are really much faster, how would nuclear power plants be affected?

Which type of respiration takes place when there is no oxygen present? a. anaerobic b. mitochondrial c. cellular d. aerobica. anaerobic

The double bond between a carbon atom and two oxygen atoms (a molecule of carbon dioxide) has two characteristics. what are they? a.an ionic bond is formed between the oxygen and carbon atoms. b.four valence electrons are shared. c.two valence electrons are shared. d.valence electrons are shared between oxygen atoms.