The human population is growing, so more food has to come from the same area of land. One biotechnological solution is genetic modification (GM). A gene from one organism is transferred into the genome of a crop plant or farm animal, so that it gains a useful characteristic. The organism is then called a GM organism.
GM crops can solve different problems. Bt maize and Bt cotton contain a gene from a bacterium that makes a protein poisonous to insect pests, so farmers need less pesticide. Herbicide-resistant crops survive being sprayed with a weedkiller, so the farmer can kill weeds without harming the crop, and the crop is not shaded or starved by weeds. Some crops are given genes that help them survive drought or salty soil, so they can be grown in places where food is hard to produce. Golden Rice has genes added so that it makes beta-carotene, which the body turns into vitamin A. This helps to prevent vitamin A deficiency, which can cause blindness in children in countries where rice is the main food.
Animals can be modified too. Some GM salmon carry an extra growth gene so they reach market size faster, producing more food from the same amount of feed. Some GM livestock are protected against disease, which cuts losses.
The benefit of a GM crop is often judged by its yield, the mass of crop grown on a given area. Percentage change in yield = change in yield ÷ original yield × 100. If a yield rises by a quarter of the original, it has increased by 25%. A rise from 10 to 12 tonnes per hectare is an increase of 2, so the increase is 2 ÷ 10 × 100 = 20%. Some people have ethical concerns about GM, and worry about safety and the effect on wildlife, so GM foods are tested and regulated.