LD50 refers to the lethal dose that kills what percentage of the test population?

LD50 refers to the lethal dose that kills what percentage of the test population?

• A. 50%
• B. 25%
• C. 75%
• D. 100%

Answer: (A)

LD50 is the dose that kills half of the test population. It’s a median lethal dose used in toxicology to compare how potent different substances are. In dose–response studies, researchers expose groups to increasing doses and see what fraction dies; the LD50 is the dose at which 50% die, which is why the number 50 appears in the name. This value can vary with species, route of exposure, and conditions, so it’s not a universal fixed number. Other points on the curve correspond to different percentages (like LD25 or LD75), and a 100% lethal dose would kill everyone, which is not the LD50.

LD50 is the dose that kills half of the test population. It’s a median lethal dose used in toxicology to compare how potent different substances are. In dose–response studies, researchers expose groups to increasing doses and see what fraction dies; the LD50 is the dose at which 50% die, which is why the number 50 appears in the name. This value can vary with species, route of exposure, and conditions, so it’s not a universal fixed number. Other points on the curve correspond to different percentages (like LD25 or LD75), and a 100% lethal dose would kill everyone, which is not the LD50.