It is difficult to distinguish the physiological races in morphology, usually relying on ( ) to distinguish them. A: differential hosts B: phenotype C: genotype D: pathogenicity

The pathogenicity of bacterium is determied mainly by ( ) A: basic structure B: specific structure C: catabolin D: invasiveness and toxin E: invade position

The main use of semi-solid medium is () A: Detection of bacterial motility B: detection of bacterial aerobic C: detection of bacterial pathogenicity D: detection of bacterial anabolism E: Detection of bacterial catabolism

Gram staining is the most commonly used staining method, and its practical significance does not include () A: Identification of bacteria B: selection of antibiotics C: understanding of bacterial pathogenicity D: understanding of cell staining E: observing the special structure of bacteria

Gram staining is the most commonly used staining method, and its<br/>practical significance does not include () A: Identification<br/>of bacteria B: selection of antibiotics C: understanding of bacterial<br/>pathogenicity D: understanding of cell staining E: observing the<br/>special structure of bacteria

The exfoliative toxins, TSST-1, and the enterotoxins are all superantigens. The genes for these toxins are A: Present in all strains of Staphylococcus aureus B: Widely distributed on the staphylococcal chromosome C: On both the staphylococcal chromosome (TSST-1 and exfoliative toxins) and on plasmids (enterotoxins) D: On the staphylococcal chromosome in a pathogenicity island E: On plasmids