Plant genetic engineering raises exaggerated expectations and induces fear in parts of the population. Plants, like all other known living organisms, pass on their traits using DNA. Plants however are unique from other living organisms in the fact that they have chloroplasts. Genetic modification has been the cause for much research into modern plant genetics, and has also lead to the sequencing of many plant genomes. The gene gun method is also referred to as "biolistics" (ballistics using biological components). This technique is used for in vivo (within a living organism) transformation and has been especially useful in monocot species like corn and rice. Transformation via Agrobacterium has been successfully practiced in dicots, i.e. broadleaf plants, such as soybeans and tomatoes, for many years. Extract of the plants has ability to protect the cells of the DNA from the attack of the chemicals, xenobiotics and other compounds that damages the cells. Free radicals when in the excess concentration, cause severe damage to nitrogen bases of the specific region of the DNA which ultimately damaged due to large chain of the free radicals.