Biotechnology is the broad field that uses living organisms or their systems to modify products, processes, or technologies. Within that broad field, genetic engineering is a specific technique that directly manipulates genetic material—DNA sequences—to achieve a desired trait or outcome. Because biotechnology covers many approaches beyond gene manipulation, while genetic engineering focuses specifically on altering genes, the statement correctly identifies biotechnology as the wider discipline and genetic engineering as the particular method within it. For example, producing insulin in bacteria using recombinant DNA is an instance of genetic engineering, whereas processes like fermentation to make cheese or yogurt illustrate biotechnology in action without necessarily involving gene editing. This relationship—biotechnology as the broad field and genetic engineering as a targeted genetic manipulation technique—best captures their distinction.

The key idea is that transcription from a T7 promoter requires a specific enzyme: T7 RNA polymerase. This promoter is tailored for the phage enzyme and is not efficiently recognized by the host’s RNA polymerase. In common bacterial expression strains, you provide T7 RNA polymerase (often from a DE3 lysogen or a plasmid under an inducible promoter) so that, when you induce, the T7 RNAP binds the promoter and drives strong transcription of the downstream gene. Without T7 RNA polymerase, the host RNA polymerase won’t initiate well at the T7 promoter, so expression would be very low or absent. The T7 promoter isn’t a replication origin, so it doesn’t drive DNA replication.

AZT works because it’s a nucleoside analog designed to halt DNA synthesis. It looks enough like thymidine to be used by viral reverse transcriptase, but after it’s converted inside the cell to its triphosphate form, it’s incorporated into the growing DNA strand. The crucial detail is that it has a 3' position missing a hydroxyl group, so once AZT is added, there’s no 3'-OH available to form the next phosphodiester bond. That stops the chain from extending, effectively terminating DNA synthesis. This is different from blocking transcription, which would stop RNA polymerase from making RNA rather than stopping DNA chain elongation. It’s also not a DNA methyltransferase or a ligase enzyme, which have distinct roles in modifying DNA bases and sealing nicks or joining fragments, respectively. So AZT is best described as a nucleoside analog that terminates DNA synthesis.

DNA produced by combining sequences from different sources is called recombinant DNA. This happens when fragments from two or more organisms are joined to form a single molecule that contains genetic material from distinct origins. Enzymes like restriction endonucleases cut the DNA, and DNA ligase seals the pieces together, creating a construct that can be propagated in a host cell. Often researchers insert recombinant DNA into a vector, such as a plasmid, to transfer it into bacteria or other cells for expression. A GMO refers to the organism that carries recombinant DNA, not the DNA molecule itself. A plasmid is a small circular DNA molecule used as a carrier, and a vector is the DNA that carries foreign DNA into a host cell—plasmids are a common type of vector. Thus, recombinant DNA is the correct description of the DNA produced by combining DNA from different sources.