The population of the mice would most likely increase. This is because the number of predators of mice will decrease. Predators are those that feed on others, in this case mice. When predators decrease, the prey (which would be the mice) will be able to populate thus leading to an increase in population.
A good model would be a simple plant taking in sunlight, carbon dioxide (CO2), and water (H2O). Then, releasing glucose and oxygen.
A specises that is very close to extinction that they are trying to save