Genetics Extensions Mendelian Inheritance Practice Test – Comprehensive Exam Prep 2025

Pleiotropy occurs when a single gene influences multiple phenotypic traits. In the case of sickle cell anemia, the gene responsible not only affects the shape of red blood cells, causing them to take on a characteristic sickle shape, but also leads to various health complications. This includes increased susceptibility to infections, pain crises, and anemia due to reduced oxygen-carrying capacity. Therefore, the impact of the sickle cell gene extends beyond just blood cell morphology to multiple aspects of an individual's health, demonstrating the principle of pleiotropy effectively.

On the other hand, options that might seem relevant highlight different genetics concepts. The first option relates to the influence of height on health issues primarily reflects a complex trait influenced by multiple genes and environmental factors, rather than being a classic example of pleiotropy. The second option focuses on a specific trait (lactose intolerance) linked to a gene, but it does not demonstrate pleiotropy since it primarily affects a single trait. The last option, which discusses two different genes affecting plant color, refers to polygenic inheritance or gene interactions, rather than pleiotropy, as it involves multiple genes contributing to one phenotypic expression.