Bacterial Structure and Staining

The scanning electron micrograph (SEM) shown above displays bacteria with a characteristic morphology. Which of the following best describes the Gram stain appearance of this organism?

Which feature best discriminates between acid-fast bacteria (e.g., *Mycobacterium tuberculosis*) and non-acid-fast Gram-positive bacteria (e.g., *Staphylococcus aureus*)?

A 32-year-old woman from Delhi presents with a chronic cough and constitutional symptoms. Sputum smear microscopy shows acid-fast bacilli. Which investigation is the gold standard for confirming the organism and determining drug susceptibility?

Which of the following bacterial structures is composed of peptidoglycan and is responsible for maintaining cell shape and rigidity?

In Gram staining, which of the following is the mordant that forms a complex with crystal violet and allows retention of the dye in Gram-positive bacteria?