Energy flows into an ecosystem as and leaves as

Recombinant dna (rdna) creates offspring which are genetically identical to the parent is the process of breeding only organisms with desirable traits involves the removal of the nucleus of a cell combines genes from organisms of different species in a lab

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.

Ascientific idea becomes valid when it is what?