Why do chromosomes often appear with an X shape in diagrams and in photos taken through a microscope

After which event could you say that evolution has occurred? question 1 options: an allele frequency changes in a population. a white-eyed fly is born into a population of brown-eyed flies. a new predator comes into an environment. an animal gets fat.

Set comes up with for examples of sound waves ocean wave light wave and hand wave which of tonys examples is not an actual scientific wave

In an experiment examining the effects tai chi on arthritis pain, callahan (2010) selected a large sample of individuals with doctor-diagnosed arthritis. half of the participants immediately began a tai chi course and the other half (the control group) waited 8 weeks before beginning. at the end of 8 weeks, the individuals who had experienced tai chi had less arthritis pain that those who had not participated in the course.