A polypeptide that has a net positive charge at physiologic pH (~7.4) would most likely contain amino acids with R groups of what type

lizards have adapted to life in the desert. some desert lizards have toes with spiny scales to them run across the sand without sinking. some use the sand to hide from predators, or to search for small animals that they prey upon.

frogs. the lower the ph the higher the acid content. frogs have the highest tolerance in this scenario.