Which of the following best describes why  invertebrates  isn't considered a scientifically valid word when classifying animals?  

Which layer will become saturated first when rain falls?

Which short-term environmental changes would a very small asteroid or comet impact on earth most likely cause? check all that apply. flooding extinction craters on surface changes in weather patterns death of organisms and populations

What are antigens and antibodies? how are they involved in the body’s response to incompatible blood?