According to Mendel's Experiments, an Allele Can Be Dominant or Recessive

Essay

According to Mendel's experiments, an allele can be dominant or recessive. A pea plant carrying one tall and one short allele will be tall because tall is dominant. It won't be some medium height. For sickle cell though, normal HbA is dominant and sickle HbS is recessive, yet a person with both of these alleles will have a mild case of sickle cell. Was Mendel wrong? Explain?