Solution : Three modes of DNA replication 1) Semi conservative: => Each daughter strand is composed of one old DNA strand and one new DNA strand. 2) Conservative: => The original double helix remains as complete unit. => The new DNA double helix is produced as a single unit. => The old DNA is completly conserved. 3) Dispersive mode: =>Separation of the individual covalent phosphodiester bonds is required for this mode of replication..