Viruses are obligate intracellular parasites that depend entirely on the host cell's machinery for replication and metabolic processes, including energy generation. They lack the enzymes and cellular structures, such as ribosomes and mitochondria, necessary for independent energy production. While some viruses can be cultured in artificial media, it usually requires living cells or specific biochemical conditions, making a general statement about culturing in 'any synthetic medium' incorrect. Furthermore, viral transmission occurs through various routes, including direct contact, aerosols, contaminated surfaces, and food/water, not solely by biological vectors.