I believe that the answer is biosphere<span />
The protein inside (a) red blood cells that carries oxygen to cells and carbon dioxide to the lungs is (b) hemoglobin. Hemoglobin is made up of four symmetrical subunits and four heme groups. Iron associated with the heme binds oxygen.
the answer is gene- the combined DNA from your mom and dad which makes up your full set of DNA.
If they live in a river, they would most likely need fins (to swim) and gills (to breathe under water)
Hope this helps!
Bacteria does not contain membrane boung organelles therefore are prokaryotic and I also know they are unicellular. and they are definitely not multicellular so the answer is : c