Which process would most directly depend on DNA?

The process that most directly depends on DNA is protein synthesis. DNA, or deoxyribonucleic acid, contains the genetic instructions that guide the synthesis of proteins, which are essential for various cellular functions and structures within an organism.

During protein synthesis, the information encoded in DNA is first transcribed into messenger RNA (mRNA). This mRNA then travels from the nucleus to the ribosomes, where it serves as a template for the assembly of amino acids into a specific protein through a process called translation. Therefore, without DNA, the instructions to create proteins would be unavailable, making it the crucial determinant in this process.

In contrast, while processes such as photosynthesis and cellular respiration are essential for energy production and overall cell function, they do not directly hinge upon the DNA sequence for their operation. Fermentation, a metabolic process that occurs in the absence of oxygen, also relies on enzymes and substrates but does not involve DNA in the way that protein synthesis fundamentally does. Thus, protein synthesis is the most DNA-dependent process among the choices given.