I. Introduction. 1  The petroleum industry began with the successful drilling of the first commercial oil well in 1859, and the opening of the first refinery two years later to process the crude into kerosene.
The cause of Down syndrome is one of three types of abnormal cell division involving chromosome 21. All three abnormalities result in extra genetic material from chromosome 21, which is responsible for the characteristic features and developmental problems of Down syndrome.
Down Syndrome. Down Syndrome is a leading cause of mental retardation. Down Syndrome is a genetic condition caused by an extra chromosome. Students with Down Syndrome have distinct physical features.tudents with Down Syndrome exhibit a wide range of behaviors and abilities, however, most have some degree of mental retardation. Language and motor development are usually slow, and speech articulation may be poor.