In the Late 1960s, Carroll Williams and Karel Salma Discovered

question 123

Multiple Choice

In the late 1960s, Carroll Williams and Karel Salma 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)some evolutionary divergence in the structure of juvenile hormone and in the juvenile hormone receptors of different insects has occurred.
• C)not all insects use juvenile hormone to stimulate metamorphosis.
• D)other insects have evolved methods to detect the juvenile hormone analog, and
• E)these insects avoid balsam firs.

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