APES Toxins, Toxicology, Bioaccumulation & Biomagnification (Unit 8)

A pesticide was applied to a population of roaches, and it was determined that the LD50 was 55 mg/kg. If the average mass of a roach was 0.02kg, which of the following approaches will determine the dose in mg per roach?

55mg/1 kg × 0.02kg

Based on the LD50 values, which of the following best describes the toxicity level of the household substances shown in the table?

Antifreeze is more toxic than aspirin.

Some toxic compounds are ingested and retained in the tissues. These pollutants pose special risks to humans and other organisms high on the food chain because of which process?

Biomagnification

An individual is exposed to the water in the stream from which the sample show in the graph was taken. If the individual was exposed to the highest dose of the bacteria, which of the following bacteria would have the lowest probability of causing illness if ingested?

C. jejuni

Which of the following best describes why DDT is classified as a persistent organic pollutant?

DDT is very stable, and as much as 50% of the original concentration can remain in the soil 15 years after the initial application.

For a certain insecticide, the LD-50 dosage level for rats is determined to be 250 milligrams per kilogram of body mass. On the basis of this information, which of the following is the best prediction regarding the consequences of receiving this dosage of the insecticide?

Five hundred out of every one thousand rats would die.

Endocrine disruptors directly affect which of the following in an organism?

Hormones

An experiment was carried out to determine the lethal dose of ammonium sulfate on mung bean germination. True statements about the experimental design include which of the following? I. The control group has neither the seeds nor the ammonium sulfate. II. The independent variable is the concentration of the ammonium sulfate. III. The dependent variable is the number of seeds that failed to germinate.

II and III only

Which of the following is the most likely consequence of runoff transporting chemicals that are endocrine disruptors to a pond?

Increased frequency of birth defects in fish populations in the pond

Which of the following best explains why top predators can have up to 60 times as much of persistent organic pollutant (POP) as their prey and up to 600 times as much of the pollutant as producers?

POPs accumulate in the body fat of living organisms. POPs increase in concentration as they move up the food chain.

If all four of the bacteria species shown in the graph are equally likely to contaminate agricultural products at a dose of 10^2 CFU, regulating which of the following species would have the greatest effect in reducing the likelihood of illness in humans?

Salmonella

Many synthetic chemicals, such as PCBs, act as estrogen mimics. In an ecosystem, these persistent chemicals would have the greatest effect on which of the following?

Secondary Consumers

Scientists are interested in determining if selenium, from a nearby mine, magnifies in the tissues of fish living in a lake. Which of the following best describes a testable hypothesis for the study?

Selenium will be at a higher concentration in fish tissue than in the tissue of fish prey.

Some studies have indicated that global amphibian populations are declining and that exposure to herbicides in agricultural runoff is implicated in the decline. Which of the following is the most likely explanation of how herbicides affect amphibians?

The herbicides act as endocrine disruptors