A good exmple of such a crop is genetically modified cotton, which is often grown in the United State for cottonseed oil. If a crop can kill pests, the farmer does not have to spray so often to kill pests. An example of a pest-resistant crop is maize, which is similar to corn. There is a bacterium in the soil which produces a poison that kills insects, but it is harmless to people. Putting this bacterium gene into maize plants makes them produce their own poison, which kills the pests that eat them. This is better for the environment because it reducesn the need to spray fields with pesticides and fertilizers.
Genetically modifide crops may make food more nutritioud by adding genes to produce more vitamins that the body needs for health and growth.