A. they arose out of Africa less than 200,00 years ago
Hello There! ^_^
Your question: What gas found in cigarette smoke and automobile exhaust, blocks the transport of oxygen by hemoglobin in the blood..?
Your answer: Carbon Monoxide is the gas that is found in cigarette smoke and automobile exhaust, blocks the transport of oxygen by hemoglobin in the blood.
Hope this helps! :D
The mass extinctions that occurred 250 million years ago and 65 million years ago may have been due to gradual process or Catastrophic events.
A 'red' apple does not emit red light. Rather, it simply absorbs all the frequencies of visible light shining on it EXCEPT for a group of frequencies that is perceived as red, which are REFLECTED. An apple looks red to us because it REFLECTS infrared waves.
