Question

1. Roundup Ready crops have been blamed for the decline over the last decade of the migratory population of Monarch butterflies. Which factors below are most likely to be associated with Monarch population declines.

a. Cheatgrass populations have been decimated by the use of glyphosate containing products

b. POEA, the surfactant in Roundup, has killed Monarch butterfly eggs

c. Toxicity of commercial varieties of Bt corn to Monarch larvae

d. Susceptibility of Asclepias species to glyphosate, leading to decimation of their populations

e. Deforestation and fragmentation of landscapes in the central highlands of Mexico

f. The high toxicity of clothianidin, a neonicotinoid insecticide used as seed treatments for Bt corn, and the presence of its residues in corn pollen

2. The work of Tyrone Hayes at the University of California-Berkeley has suggested that atrazine herbicide disrupts the endocrine system. Some scientists suggest therefore that frogs should be used as “canaries in a coal mine” and forewarn us about the imminent danger that this herbicide poses to human fertility and development. The plausibility of such an extrapolation is weak for which of the following reasons. (Choose all reasons that support the lack of plausibility)

a.The aggregate of all research on atrazine in a quantitative weight of evidence meta analysis concluded that effects on amphibian development and growth were unlikely

b. Studies published subsequent to Hayes early research were not able to repeat the observations of effects on frogs

c. Atrazine residues are hardly ever found in food, thus exposures would be minimized.

d. Atrazine residues are hardly ever found in water, thus exposures would be minimized.

3. Although Roundup is more toxic than its active ingredient alone, cause for concern should a wetland be oversprayed is unlikely due to a short persistence time of the toxicant causing this differential effect. The reason for this short persistence time is the presence in natural waters of [__________________].

Answer 1

1. The toxicity levels of the commercial Bt corn are very high to the Monarch butterflies, that has led to a sharp decline in their numbers. Hence, the correct answer is option 'c'.

2. The plausibility of such an exploitation is weak because the studies that were published subsequent to the Hayes research could not repeat the observations. Hence, the correct answer is option 'b'.

3. The reason for the short persistence time is the presence in natural waters of organic (microbes) and inorganic substances.