A person with a genotype of HbSS has sickle cell disease. A person with a genotype of HbAS allele carries the sickle cell trait. A person with a genotype of HbAA does not have sickle cell disease and does not carry the trait. The Punnett square shows the genotype of two people carrying the sickle cell trait.

supercell thunderstorms are perhaps the most violent of all thunderstorm types, and are capable of producing damaging winds, large hail, and weak-to-violent tornadoes

stimulus is a change in the environment that causes an organism to react. the response is the reaction to the stimulus. some examples of stimuli for zebras are drought, to many predators, and bad feeding grounds such as dead grass or plants. zebras respond to stimuli just like all other living organisms