In mice, the LD50 for staphylococcal enterotoxin is 1350 ng/kg, and the LD50 for Shiga toxin is 250 ng/kg.Which of the following
statements is true?a) More organisms of Staphylococcal bacteria must be ingested to cause infection, as compared to Shigella bacteria.b) Staphylococcal enterotoxin is the more lethal of the two toxins.c) Shiga toxin is more lethal than staphylococcal enterotoxin.d) The parenteral route is the preferred portal entry for Shigella bacteria.
LD50 is a measure of toxicity in animals. A chemical with a smaller LD50 is more toxic and in this question, Shiga toxin has a lower LD50, thus it is more lethal.
Pollution caused the environment to become more darkly colored, so moths were selected to be blacks and greys. Before pollution they were white and lighter colors. <span />
