The Joy of Genetic Possibilities

How many possible genotypes and phenotypes are there for a single gene trait that shows dominance in any given population?

A. One genotype, one phenotype

B. Two genotypes, two phenotypes

C. Three genotypes, two phenotypes

D. Two genotypes, three phenotypes

Answer:

The answer is C. Three genotypes, two phenotypes.

When considering a single gene trait that exhibits dominance in a population, there are three possible genotypes and two possible phenotypes. Let's take a closer look at how this works.

For instance, if we have a gene for flower colors where the A allele is dominant and the a allele is recessive, the genotypes that can result are:

  • AA
  • Aa
  • aa

However, despite there being three possible genotypes, due to the dominance of the A allele over the a allele, there are only two observable phenotypes:

  • Red flowers (genotypes AA and Aa)
  • White flowers (genotype aa)

This is why in this scenario, there are three genotypes but only two phenotypes. Understanding genetic possibilities and the interplay between alleles can be quite fascinating!

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