The main idea is that the genetic message needs to be carried from the DNA in the nucleus to the ribosome where proteins are built. This role is fulfilled by messenger RNA. During transcription, an RNA copy is made that is complementary to the DNA template strand and resembles the DNA coding strand with uracil replacing thymine. This mRNA exits the nucleus and provides the sequence that ribosomes read to assemble amino acids into a protein. Other RNA types have different jobs: transfer RNA ferry’s amino acids to the ribosome and matches its anticodon to the mRNA codon, ribosomal RNA is a structural and catalytic part of the ribosome itself, and small nuclear RNA participates in splicing pre-mRNA in the nucleus. Thus, only mRNA serves as the information carrier from DNA to the ribosome for protein synthesis.

The main concept is how transcription ends in bacteria and the specific role of the Rho protein. Rho-dependent termination needs a protein factor, Rho, to function. Rho binds to a rut site on the newly made RNA and uses ATP to move along the transcript toward the RNA polymerase. When it catches up to a paused polymerase, Rho disrupts the RNA–DNA hybrid and releases the RNA, terminating transcription. In contrast, intrinsic (Rho-independent) termination doesn’t require any protein. It relies on the RNA forming a strong hairpin followed by a string of uracils, which causes the polymerase to pause and dissociate on its own. Promoter-associated termination isn’t a separate mechanism in the same sense; termination generally occurs downstream of promoters and can be either Rho-dependent or intrinsic. Therefore, the mechanism that requires the Rho protein is the Rho-dependent termination.

Semiconservative replication means each daughter DNA molecule keeps one strand that was part of the original duplex and pairs it with a newly synthesized strand. As the parental strands separate, each serves as a template for a new complementary strand, so every daughter molecule ends up with one original strand and one newly made strand. That’s why the correct count is one original strand per daughter molecule. The other options describe concepts that don’t match how DNA actually replicates in cells (two original strands, zero original strands, or three), which doesn’t occur in this process.

The main idea is translation—the process by which ribosomes convert the information in mRNA into a polypeptide. During translation, the ribosome reads mRNA codons and works with tRNA molecules that bring the matching amino acids. As each codon is read, the ribosome links the new amino acid to the growing chain, forming peptide bonds and building a polypeptide until a stop codon ends synthesis. This occurs in the cytoplasm (in prokaryotes) or in the cytoplasm of eukaryotic cells, with initiation, elongation, and termination phases guiding the assembly. Transcription, by contrast, is RNA synthesis from a DNA template and does not involve the ribosome. Replication duplicates DNA, and transduction refers to viral transfer of genetic material—neither process uses ribosomes to build polypeptides.