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 extracted and observed DNA from white - blood cells in the late 19th century. He isolated a substance he called "nuclein" from the nuclei of white blood cells, which was later identified as DNA. The other options describe contributions by other scientists. Rosalind Franklin created the first photograph of the structure of DNA. Watson and Crick, with help from Chargaff's rules (discovered by Erwin Chargaff), discovered how the DNA bases pair together and created the first accurate model of DNA's structure.

Answer:

He extracted and observed DNA from white blood cells.