Environmental effects on phenotype Original Scenario-Based Download PDF

Questions

1. 1.

   In an enclosed biosphere research station, botanists cultivate vegetative clones of a rare crystal-fern (*Vitreophyton nova*) derived from a single parent plant. Clones grown in acidic potting substrate (pH 4.5) develop vibrant indigo, bioluminescent fronds, whereas identical clones grown in neutral-to-alkaline substrate (pH 7.5) develop pale silver, non-luminescent fronds under identical light, humidity, and temperature conditions. When the silver specimens are transplanted back into acidic soil, their newly emerging fronds grow vibrant indigo once again. Which conclusion is best supported by these observations?

   • A) Environmental factors regulate the expression of pigment-producing genes, resulting in different phenotypes from identical genotypes.
   • B) Directional natural selection rapidly selected for new beneficial mutations that confer indigo luminescence under acidic conditions.
   • C) Complete dominance of an allele masks recessive luminescence traits through classic Mendelian segregation in alkaline soils.
   • D) Epistatic interactions between unlinked gene pairs altered the phenotypic inheritance ratios during vegetative propagation.