(29) http://en.wikipedia.org/wiki/Image:AminoAcidball.svg. Creative Commons.
(30) http://commons.wikimedia.org/wiki/Image:Periodic_Table_Armtuk3.svg.
GNU-FDL.
(31) muscle fibers (protein). Public Domain.
marvins-underground-k-12
(Marvins-Underground-K-12)
#1