Here are the four postulates of natural selection, according to Charles Darwin:
1. variability - refers to different mutations that create different species
2. heritability - refers to the genes that are passed from one organism onto its descendants
3. overproduction of offspring - refers to the fact that more "children" is born than dies
4. natural selection - refers to those organisms that survive because they adapt to their surroundings better than those who will die
it binds to hemoglobin with greater affinity than oxygen does.
I believe the force is called diffusion.
http://www.answers.com/Q/Why_is_carbon-14_not_used_to_date_the_age_of_the_earth?#slide=1
This might help you, good luck!!