Answer: A gene is a sequence of nucleotides in DNA or RNA that encodes the synthesis of a gene product, either RNA or protein. A chromosome is a long DNA molecule with part or all of the genetic material of an organism. A allele is one of two or more alternative forms of a gene that arise by mutation and are found at the same place on a chromosome.
The independent variable is always changed by the scientist, and what happens then is known as the dependent variable because it depends on the indépendant variable!