Oort cloud: a spherical region that surrounds the solar system, that extends from the kuiper belt to almost halfway to the nearest star, and that contains billions of comets
A model organism is a species that has been widely studied to understand a particular biological phenomena, normally used because they are easy to breed and maintain in a laboratory setting and has certain experimental advantage.
The criteria that Thomas hunt Morgan was looking for include; the model organism should be small in size, easy to keep in the laboratory and also able to produce large number of off springs in a short time.
Aerobic exercise is the body producing energy WITH the use of oxygen (light activities like jogging). Anaerobic exercise produce energy without the use of oxygen and is typically a higher intensity that burns fat AND helps gain lean muscle mass (these are activities like weight lifting).
