What can happen if the needs of living things are not met?

The organism(s) will die. Any one of these needs are food, shelter, space, a safe place to raise kids, and/or water. Or the organism might have to move to a different area. That area might contain hostile creatures that would kill the organism, or it might eat something unfamiliar that was poisonous and it would die. There are stories of Jaguars who had been forced out of their home by deforestation. These jaguars are so desperate to survive that they turn to he helpless livestock of local farmers. The farmers then set out to kill the animal, and usually succeed.