In the late 1960s, Carrell Williams and Karel Slama discovered that the insect Pyrrhocoris apterus, when grown in jars with paper towels made from balsam fir, underwent several extra larval molts and finally died without completing metamorphosis
Further investigation led to
the conclusion that the fir trees synthesize a hormonal analog that acts as an insecticide. The
molecule is actually an analog of juvenile hormone. Furthermore, the juvenile hormone
analog discovered by Salma and Williams has no effect on most other metamorphosing
insects, suggesting that:
A. many insects reproduce as larvae.
B. there has been some evolutionary
divergence in the structure of juvenile
hormone and in the juvenile hormone
receptors of different insects.
C. not all insects utilize juvenile hormone to
stimulate metamorphosis.
D. other insects have evolved methods to
detect the juvenile hormone analog and are
not found in balsam firs.
B
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Countries engage in trade because
a. the exchange is mutually beneficial. b. governments force industries to exchange. c. international law dictates that exchange must take place. d. All of these.
The most notable difference between PrPC (normal protein) and PrPSc (prion protein) is ________.
A. PrPc folds appropriately whereas PrPSc does not fold correctly B. PrPC causes a cell to undergo rapid apoptosis C. PrPC is a much longer polypeptide chain, compared to PrPSc D. PrPc is a functional glycolytic enzyme whereas PrPSc is nonfunctional
Which of the following is not a true statement regarding the genetic code?
A) The genetic code is degenerate. B) The genetic code is nearly universal, with only a few minor exceptions. C) The genetic code is nonoverlapping. D) The genetic code is triplet-based. E) Each codon represents a different amino acid.
Animal viruses have been cultivated in
A. embryonated eggs. B. suitable host animals. C. tissue cultures (monolayers of animal cells). D. All of the choices are correct.