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Genetically Modified (GM) 

 What is GM?

GM, which can stand for genetic modification or genetically modified, is the
technique of changing or inserting genes. Genes carry the instructions for all
the characteristics that an organism – a living thing – inherits. They are made
up of DNA. Genetic modification is done either by altering DNA or by introducing genetic material from one organism into another organism, which can be a variety of either the same or a different species. For example, genes can be introduced from one plant to another plant, from a plant to an animal, or from an animal to a plant.
Transferring genes between plants and animals is a particular area of debate.
Sometimes the term ‘biotechnology’ is used to describe genetic modification.

What is the point of genetic modification?

There are three reasons that scientists genetically modify plants:

a) Herbicides are often used to kill weeds in fields of crops but they can also affect the growth of the crops they are intended to protect. By using genetic modification, a gene with a particular characteristic, such as resistance to a specific herbicide, can be introduced into a crop plant. When that
herbicide is sprayed on the field to kill the weeds, it will not hinder the growth of the crops.

b) Genetic modification can be used to reduce the amount of pesticide needed by altering a plant’s DNA so it can resist the particular insect pests that attack it.

c) Genetic modification can also be used to give crops immunity to plant viruses or to improve the nutritional value of a plant.

Two examples of genetically modified crops:

1) Insecticide sweet corn

Scientists have genetically modified sweet corn so that it produces a poison which kills harmful insects. This means the farmer no longer needs to fight insects with insecticides. The genetically modified corn is called Bt-corn, because the insect-killing gene in the plant comes from the bacteria Bacillus thuringiensis


The farmer no longer has to use insecticide to kill insects, so the surrounding environment is no longer exposed to large amounts of harmful insecticide.
The farmer no longer needs to walk around with a drum of toxic spray wearing a mask and protective clothing.


  • This type of genetically modified corn will poison the insects over a longer period than the farmer who would spray the crops once or twice. In this way the insects can become accustomed (or resistant) to the poison. If that happens both crop spraying and the use of genetically modified Bt-corn become ineffective.
  • A variety of insects are at risk of being killed. It might be predatory insects that eat the harmful ones or, perhaps attractive insects such as butterflies. In the USA, where Bt-corn is used a great deal there is much debate over the harmful effects of Bt-corn on the beautiful Monarch butterfly.

2) Long-lasting tomatoes

Long-lasting, genetically modified tomatoes came on to the market in 1994 and were the first genetically modified food available to consumers. The genetically modified tomato produces less of the substance that causes tomatoes to rot, so remains firm and fresh for a long time.


  • Because the GM tomatoes can remain fresh longer they can be allowed to ripen in the sun before picking - resulting in a better tasting tomato.
  • GM tomatoes can tolerate a lengthier transport time. This means that market gardens can avoid picking tomatoes while they are green in order that they will tolerate the transport.

The producers also have the advantage that all the tomatoes can be harvested simultaneously.


Scientists today can genetically modify tomatoes without inserting genes for antibiotic resistance. However the first genetically modified tomatoes contained genes that made them resistant to antibiotics. Doctors and vets use antibiotics to fight infections. These genes spread to animals and people so doctors would have difficulties fighting infectious diseases.