You are observing a Gram stain of spherical-shaped microorganisms that are linked in a chain and stain purple. How would you describe these bacteria using the correct terminology for the cell shape and arrangement?

a) gram-positive tetrads

b) gram-positive coccobacilli

c) gram-positive streptococci

d) gram-negative staphylococci

The correct answer is option c) "gram-positive streptococci".

Explanation:

Gram-positive bacteria are stained purple by crystal violet coloration, result of the cell wall interaction with the dye. On the other hand, streptococci are spherical-shaped microorganisms linked in a chain or a raw, which also are gram-positive. Therefore, the correct terminology of the bacteria observed in the laboratory will be a gram-positive streptococci.