(a) Write the scientific name of the organism Thomas Hunt Morgan and his colleagues worked with for their experiments. Explain the correlation between linkage and recombination with respect to genes as studied by them.
(b) How did Sturtevant explain gene mapping while working with Morgan?

OR

(a) State the ‘Central dogma’ as proposed by Francis Crick. Are there any exceptions to it? Support your answer with a reason and an example.
(b) Explain how the biochemical characterisation (nature) of ‘Transforming Principle’ was determined, which was not defined from Griffith’s experiments.

(a) Drosophila melanogaster. Higher the linkages between two genes, the lesser the chances of recombination.
(b) Recombination frequency between gene pairs is the measure of the distance between genes on the same chromosome and Sturtevant mapped their positions on the chromosome.

OR

(a)
 

Viruses containing RNA as their genetic material is the exception.

(b) Biochemical characterization (nature) of the transforming principle was given by Oswald Avery, Colin MacLeod, and Maclyn McCarty. They conclude from the experiment that digestion with DNase did inhibit transformation. DNA is the hereditary material.