Explain two reasons why having an oxygen-rich atmosphere is important for pife on Earth?

Which blood cell spend most of their time in the lymphatic system?

Which greenhouse gas is emitted when burn fossil fuels for energy? a. nitrogen b. oxygen c. carbon dioxide d. helium

Which best describes a benefit of using dna technology in medicine? a) medicine can be produced in mass quantities. b) medicine can be distributed at a reduced cost. c) medicines have fewer side effects. d) medicines are resistant to antibiotics.