DNA transfer by conjugation is more efficient in a liquid medium setting, subjected to very mild agitation (stirring), rather than on an agar plate format. Why?

The cell to cell contact is more likely to occur in mild agitation.

Explanation:

Conjugation may be defined as the process of exchange of genetic material through the formation of bridge. This is a type of mechanism of the horizontal gene transfer.

The cell to cell contact is important for the process of conjugation. The conjugation process is more efficient in liquid media as the cell to cell contact is more possible by stirring or mild agitation. The cells grown on agar plate formation has less chance to undergo conjugation.