Question

what was friedrich mieschers contribution to the discovery of the genetic code? he created the first photograph of the structure of dna. he discovered how the dna bases pair together. he created the first accurate model of dnas structure. he extracted and observed dna from white blood cells.

Explanation:

Friedrich Miescher was the first to isolate and observe DNA. He extracted it from white blood cells in 1869. The first photograph of DNA's structure (Rosalind Franklin's X - ray diffraction image) came much later. The discovery of how DNA bases pair together (Watson and Crick, with contributions from Chargaff) and creating the first accurate model of DNA's structure (Watson and Crick) also occurred after Miescher's work.

Answer:

He extracted and observed DNA from white blood cells.