How can alleles that cause serious diseases, such as sickle cell disease, still provide an advantage to the human population?

Heredity has an impact on personal health, but environmental factors are important as well. select the best answer from the choices provided

Match the reproductive structures based on their function and the system to which they belong. egg ovary sperm vas deferens vagina fallopian tube testis urethra

Has anyone taken the genetics unit test in connexus? not looking for answers, just a little bit what to expect and some with studying.