Q1. Select Francis Harry Compton Crick’s Ph.D. thesis title-
A X-ray diffraction: polypeptides and proteins Correct
B X-ray diffraction: nucleic acids
C Transformation in Streptococcus pneumoniae
D Semiconservative DNA replication model
Explanation
Francis Harry Compton Crick completed his doctoral work on X-ray diffraction, with the thesis title centred on polypeptides and proteins. That makes the polypeptides-and-proteins title the keyed answer. Nucleic acids are linked to the later DNA structure work with Watson and others, but that wording is not his Ph.D. thesis title. Transformation in Streptococcus pneumoniae points to Griffith’s bacterial transformation experiment. The semiconservative DNA replication model is associated with the Meselson-Stahl experiment, not Crick’s doctoral thesis.