Controlled experiments are experiments that have only one variable. All other factors in the experiment are kept the same. Many hypotheses can be tested through controlled experiments, but it is not always possible to do a controlled experiment. Which of the following hypotheses most likely cannot be tested with a controlled experiment? A. A flowering plant will produce more fruit when treated with phosphate powder. B. Ultraviolet radiation can cause genetic mutations in bacteria. C. Gravitational force is affected by both mass and distance. D. In the wild, chimpanzees form social groups composed of 10 to 20 individuals.

parasites can detrimentally affect their host, but also must not allow their host to die before they can complete their life cycle. some parasites have complex life cycles with many different hosts, and have had to find ways of persisting in many different environments during the change from one host to another. ectoparasites live outside the body of the host, and can more easily  disperse, but are  more exposed to predators, parasites, parasitoids. endoparasites live inside the body of the host, and are therefore protected from the outside environment. but they can be  attacked by the host's immune system. they have therefore developed  mechanisms for dispersal such as  complex life cycles.