How does commensalism affect the ecosystem?

What would be the most logical reason that a baby would measure 4 weeks ahead on an ultrasound and can a scan be that much off? What does 1C1 mean on a ring marked 10kp? When encountering vessels in the darkness what do visible white and green lights indicate? Food chain for chickens? What percentage of the surface of Venus could be characterized as continental sized highlands? What item is used for measuring wheight? When during the light reaction is the water molecule split? What is a list of the discoveries found by Copernicus? What are basis in a crystal structure of solid? In which year Invention of radio? How would you describe a lipid molecule? When a magnet is suspended in freely still air then which direction the north pole will rest? How many sweat glands does an adult have in the dermis? What is the 92nd element in the periodic table? Do black holes use gravity? Is an organism that eats the remains of dead organisms called herbivores? When did Mt Pinatubo erupted? Why cant water exist in liquid form on mars and the other outer planets? Why do homestyles change? Managers are often referred to as?