Consider the following statements and select the correct statements -

a. DNA replication is a semi-conservative process

b. DNA replication is a semi-discontinuous process

c. DNA polymerase III is responsible for replacement of the primer sequence of the Okazaki fragments

d. Primer is synthesized on both the strands of the DNA

The correct answer is a, b, and d.

Concept:

DNA replication

• DNA replication occurs in all living organisms.
• It is an important biological process for inheritance.
• It is an enzyme-catalyzed reaction.
• The main enzyme in the DNA replication process is DNA Polymerase.
• A DNA molecule replicates itself to create two identical copies.

Explanation:

DNA replication is a semi-conservative process (correct)

• Watson and Crick in 1953 proposed a scheme that DNA replication was semi-conservative.
• Replication is semi-conservative because the two parental strands separate and each strand acts as a template for synthesizing a complementary strand over it.
• After completion of replication, each DNA had one parental strand and one newly synthesized strand.

DNA replication is a semi-discontinuous process (correct)

• DNA replication is a semi-discontinuous process because two complementary strands are synthesized during replication and run anti-parallel. 
• The DNA polymerase can only add nucleotides to the 3' end of a DNA strand.
• As a result, one strand is synthesized continuously, known as the leading strand, and the other is synthesized discontinuously, known as the lagging strand.

DNA polymerase III is responsible for the replacement of the primer sequence of the Okazaki fragments (incorrect)

• DNA polymerase III synthesizes a new DNA strand in 5'→3' direction, antiparallel to the template strand.
• DNA polymerase I remove RNA primer nucleotides with its  5'→3' exonuclease activity and replaces them with complementary DNA nucleotides by its 5'→3' polymerisation activity.

Primer is synthesized on both the strands of the DNA (correct)

• Before DNA replication can occur, a primer must be synthesized by an enzyme called primase, which is a type of RNA polymerase. 
• Because the enzymes that synthesize DNA, known as DNA polymerases, can only attach new DNA nucleotides to an existing strand of nucleotides, the synthesis of a primer is required.