There are approx 100 billion
Stem cells can specialize into any type of cell in the body
Answer:
Option C
Explanation:
Given -
Total number of initially marked lizards (M) 
Total number of recaptured lizards (C) 
Total number of recaptured marked lizards (R) 
As we know that -

We have to find "N" . "N" is the total population size of lizards in a 2-hectare plot in eastern Arizona.
Thus, on rearranging the above equation, we get -

Substituting the given values in above equation, we get -

Hence, option C is correct
When we breathe in, oxygen enters our lungs and enters small sacs in our lungs called the alveoli. In the alveoli, the oxygen diffuses INTO the bloodstream through small blood vessels, called capillaries, that surround these alveoli. The oxygen is now in our bloodstream instead of our lungs and is used in cell respiration etc.
Oppositely, carbon dioxide is diffused FROM the bloodstream TO the alveoli, also through these capillaries. The carbon dioxide is now in the lungs instead of the bloodstream and when you breathe out, the carbon dioxide is breathed out out of your lungs.
Hope this helped, even if it helped a tiny bit. :)