Final answer:
The modified fish are able to produce new growth hormones because their cells contain a gene from another species, facilitated by recombinant DNA technology. This gene is transcribed and translated to produce the hormone, with applications of this technology found in medicine and agriculture.
Step-by-step explanation:
The genetically modified fish are able to produce the new growth hormone because (1) each of their cells contains the new gene to produce growth hormone.
This is achieved through recombinant DNA technology, which allows a gene from one species to be inserted into the genome of another species. This inserted gene is then transcribed and translated within the host organism's cells, leading to the production of the new protein - in this case, a growth hormone from a different fish species.
Through genetic engineering, the DNA inserted into the fish directs the cells' own machinery to synthesize the desired hormone. It's important to note that the fish's modified body cells reproduce via mitosis, not meiosis (eliminating option 4).
Applications of recombinant DNA technology are widespread, including the production of human insulin, human growth hormone (HGH), and development of transgenic plants and animals. For example, HGH used to treat growth disorders in children is produced using engineered E. coli, demonstrating the versatility of genetic engineering in producing various proteins.