In the construction of chromosome maps, the evidence is derived mainly from
Cross over values
Hereditary effects of chromosome fragmentation
Electron microscopy
Behaviour of chromosomes during meiosis
Break through of the year $2002$
Chromosome set in zygote is
How many types of $DNA$ polymerases are present in bacteria?
Beadle and E.L. Tatum performed classical experiment on Neurospora crassa to explain