1 the set of exogenic (physical, chemical and biological) processes that alter the physical and chemical state of rocks at or near the earth's surface.  intensity of most weathering decreases with depth, because variations in temperature and moistures decrease with depth.
A gene is a segment of nucleic acid that contains the information necessary to produce a functional product, usually a protein. Genes consist of a long strand of DNA (RNA in some viruses) that contains a promoter, which controls the activity of a gene, and a coding sequence, which determines what the gene produces.
The order (or sequence) of these four bases determines each genetic code. The segments of DNA that contain the instructions for making specific body proteins are called genes. Scientists believe that human DNA carries about 25,000 protein-coding genes. Each gene may be thought of as a recipe you'd find in cookbook.