I suggest this sentence be changed into:
この物質はどのように体に吸収されるのか知りたいです。
この物質がどのように体に吸収されるのか知りたいです。(sounds more natural to me)
For indirect questions we use either のか or か like these:
どうして彼が嫌いなのか説明してくれない?
どこに行けばいいのかわからない。
お昼どこで食べるか決めたの?
Thanks. Indeed subject within a matrix sentence should be が and not は. And indirect clause is always marked by か.
Etîketî
Heme etîketan bivîneLîsteyî
Sentence text
License: CC BY 2.0 FRDekewtişî
Na cumle verî sey açarnayîşê cumleya #845134
hetê tigro1973ra ame îlawekerdene, August 28, 2011
hetê tigro1973 ra ame girêdayene, August 28, 2011
hetê tigro1973 ra ame pergalkerdene, August 29, 2011
hetê Scott ra ame girêdayene, September 5, 2011