Here's why:

* Chromosomes are long strands of DNA that contain genetic information. They are found in the nucleus of cells.

* Genes are specific segments of DNA located on chromosomes. Each gene carries instructions for building a particular protein or regulating a specific function in the body.

* Proteins are essential for various bodily functions, from building tissues to regulating metabolism.

* The combination of genes inherited from both parents determines an organism's characteristics, also known as its phenotype. These characteristics can range from physical traits like eye color and height to more complex features like susceptibility to certain diseases.

Therefore, genes, found on chromosomes, are responsible for determining the specific characteristics of an organism.