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.
The temperature of Earth's surface would be SIGNIFICANTLY LOWER. This is due to water vapor's critical need to help warm and support life
Darwin's "Origin of Species" and Lamark's "Theory of Inherited Characteristics"
the outermost region of a planet's atmosphere
