Statement I : Restriction endonucleases are also called ‘molecular scissors’.

Statement II :When fragments generated by restriction endonucleases are mixed, they join together due to their sticky ends.

Both statements I and II are correct .

Statement I: True, restriction endonucleases are often referred to as "molecular scissors" because they can cut DNA at specific recognition sites, creating fragments with sticky ends.

Statement II: True, when fragments generated by restriction endonucleases have sticky ends, they can join together through complementary base pairing. The sticky ends have unpaired nucleotides that can hydrogen bond with complementary bases on other DNA fragments. This base pairing allows the fragments to temporarily bind together. DNA ligase then helps to form covalent bonds between the adjacent nucleotides of the fragments, permanently joining them into a continuous DNA molecule. This process is crucial in creating recombinant DNA molecules during gene cloning and other genetic engineering techniques.