AP Environmental Science Practice Quiz: Lethal Dose $50\%$ ($ ext{LD}_{50}$)
Written by AP Content Team, Verified for 2026 AP Exams, Last updated: May 2026
Test your understanding with short quizzes. This quiz has 7 questions to check your progress.
Question 1 of 7
All Questions (7)
A) Lethal Dosage for 50 individuals
B) Limited Dose for 50% of a population
C) Lethal Dose 50%
D) Lowest Dose for 50% of a population
Correct Answer: C
The provided content explicitly defines the term as Lethal Dose 50% (LD50).
A) expected to survive the dose.
B) fatally affected by the dose.
C) immune to the chemical.
D) exposed to the chemical.
Correct Answer: B
According to the definition, LD50 is the dose of a chemical that is lethal to 50% of the population, meaning this percentage is fatally affected.
A) The dose of a chemical that makes 50% of a population sick.
B) The dose of a chemical that is lethal to 100% of a population.
C) The dose of a chemical that is lethal to 50% of the population of a particular species.
D) The dose of a chemical that is safe for 50% of the population of a particular species.
Correct Answer: C
This option is a direct restatement of the definition provided: 'Lethal dose 50% (LD50) is the dose of a chemical that is lethal to 50% of the population of a particular species.'
A) environmental condition.
B) dose of a chemical.
C) type of radiation.
D) biological pathogen.
Correct Answer: B
The definition explicitly states that LD50 is the 'dose of a chemical,' which is a measure of that chemical's toxicity.
A) The entire population will perish.
B) The entire population will survive.
C) Approximately half of the population will perish.
D) Exactly 50 individuals in the population will perish.
Correct Answer: C
Based on the definition, the LD50 is the dose lethal to 50% of the population. Therefore, it is expected that approximately half, or 50%, of the population will die.
A) particular time of year.
B) particular ecosystem.
C) particular species.
D) particular laboratory.
Correct Answer: C
The provided text specifies that LD50 is determined for 'the population of a particular species,' indicating that the value is species-specific.
A) sickness.
B) death.
C) sterility.
D) mutation.
Correct Answer: B
The word 'lethal' means causing or sufficient to cause death. Therefore, the definition refers to the dose that is fatal to a portion of the population.