Answer:
Evolution of cells.
Explanation:
The hypothesis that eukaryotic cells evolved from a symbiotic association of prokaryotes—endosymbiosis—is particularly well supported by studies of mitochondria and chloroplasts, which are thought to have evolved from bacteria living in large cells.
“No one knows how and why people change as they get older. Some theories claim that aging is caused by injuries from ultraviolet light over time, wear and tear on the body, or byproducts of metabolism. Other theories view aging as a predetermined process controlled by genes.”
Positive reinforcer
<span>positive reinforcement can lead to adverse effects, and it is implicated in a range of personal and societal problems. If used inappropriately or in excess, it can change the health of a client negatively. </span>