Tornadoes only form under certain weather conditions. There are three types of airs for a tornado to form, warm humid air close to the ground, cold air in the upper atmosphere, and hot dry air on top that form a cap.(na, 2010) Hurricanes can form tornadoes adding to their destructive power.
Genetically modified crops. Genetically modified crops (GM crops, or biotech crops) are plants used in agriculture, the DNA of which has been modified using genetic engineering techniques. In most cases the aim is to introduce a new trait to the plant which does not occur naturally in the species.
Scientists discovered in 1946 that DNA can transfer between organisms. The first genetically modified plant was produced in 1983, using antibiotic-resistant tobacco. In 1994, the transgenic Flavr Savr tomato was approved by the FDA for marketing in the US.