Which nitrogenous base is not present in $RNA$?

Which scientists proposed the complete and systematic model of $DNA$?

Who proposed the following statement?
"It has not escaped our notice that the specific pairing we have postulated immediately suggests a possible copying mechanism for the genetic material."

Which amino acids are present in high amounts in histone proteins?

Which is the functional unit of inheritance?

With which nitrogenous base does $Adenine$ pair?