Ashort, nonsmoking middle-aged man presents to the emergency room with left-sided chest pain and a cough. he says that the pain started abruptly, just after lunch, and that breathing and coughing make it worse. he denies recent injury. he is breathing shallowly and rapidly and expresses fear that he may be having a "heart attack." breath sounds are normal, and he is not cyanotic. which condition is most likely causing his symptoms?

Juan and carol were studying invertebrates in biology. they knew that segmented or earth worms preferred a dark, moist habitat. during this lab, they would be investigating the responses of organisms called planaria or dugesia tigrina. these were simple flatworms that still had a one-way digestive system and a very simple nervous system. juan and carol placed the planaria in a petri dish containing cool, distilled water that was partially covered with black paper. they shined a light on the dish. next, they removed the paper and placed a small amount of chicken liver at one end of the dish. they added a few large salt crystals to the water. finally, they added drops of hot water to the cool water in the petri dish. their results can be seen in the data table. according to their experiment, all but one conclusion is valid.