Final answer:
The physical appearance of colonies of Streptococcus pneumoniae is related to the presence or absence of a capsule. The presence of the capsule can make the colonies appear smooth, while the absence of the capsule can make them look rough.
Step-by-step explanation:
The physical appearance of colonies of Streptococcus pneumoniae is related to the presence or absence of a capsule. The capsule is a polysaccharide coating that covers the bacterial cells. The presence of the capsule can make the colonies appear smooth, while the absence of the capsule can make them look rough.