Why is chlamydia known as the "silent" sexually transmitted disease?

Which of the follow describes a disadvantage secondary sources have compared to primary sources?

Amarine ecologist has constructed the conceptual model shown in the diagram. what predictions can be made from using this model? where the tertiary consumers get their energy how often primary producers are able to reproduce when bacteria and fungi initiate the process of decomposition whether other secondary consumers are present

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.