For the body to function normally, the organs and tissues must communicate to control the development of the cells and tissues. if there is a break-down in this communication, uncontrolled cell growth in one part of the body could impede the development of other cells or tissues. this, in turn, can lead to the normal functions of the individual becoming seriously impaired. research has shown that this uncontrolled cell growth and development can lead to which of these diseases? a) aids b) cancer c) hemophilia d) down syndrome

affects the water bodies: excessive use of fertilizers causes eutrophication. the fertilizers which are used on plants affect the quality of land on which it is used, further causing erosion of soil. the fertilizers used on plants contain harmful chemical fumes which affect the environment.

the nitrogen cycle provides nitrogen to the ecosystem from the atmosphere, ground and oceans. nitrogen is an important component of complex molecules such as amino acids and nucleotides, which lead to the creation of proteins and dna, the building blocks of all life. plants absorb nitrogen in the form of ammonium, nitrate ion and, on rare occasions, as amino acids. animals receive nitrogen necessary for biological processes from feeding on living or dead organic matter.