Final answer:
The long chains of spherical cells lacking membrane-bound organelles indicate a bacterial infection, specifically strep throat.
Step-by-step explanation:
The long chains of spherical cells that lack membrane-bound organelles indicate a bacterial infection. This is because bacteria are prokaryotic organisms that lack membrane-bound organelles, such as nuclei, mitochondria, and endoplasmic reticulum. Viruses are not composed of cells and fungi have membrane-bound organelles, so they can be ruled out.
Furthermore, the doctor's diagnosis of strep throat suggests a bacterial infection. Streptococcus pyogenes, the bacteria responsible for strep throat, can be identified through a throat culture. Antibiotics are prescribed to kill the bacteria, which wouldn't be effective against viral or fungal infections.