Under what circumstances will a recessive gene be expressed? a. when the gene is carried on the y chromosome b. when the gene is from the mother c. when it is paired with another recessive gene for the same trait or d when it is carried on the x chromosome.

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.