In biological terms, what defines a somatic cell?

A somatic cell is defined as any cell that is not a reproductive cell, which means it encompasses all the cells that make up the bodies of multicellular organisms, excluding the gametes (sperm and egg cells). Somatic cells are responsible for all the bodily functions, development, and growth of the organism, as they include muscle, nerve, skin, and blood cells, among others. This definition clearly identifies somatic cells as those that are involved in the structural and functional systems of the organism rather than contributing to the process of reproduction.

The other choices highlight specific types of cells or functions that do not align with the definition of somatic cells. For example, the option related to cells involved in immune response focuses on a particular function but does not encompass the broader range of somatic cells. Similarly, a reproductive cell directly contradicts the concept of somatic cells as it explicitly refers to gametes. Lastly, the option addressing photosynthesis is not relevant to somatic cells, as this process is primarily associated with plant cells, specifically chloroplasts in those cells, and does not define a somatic cell in organisms that do not perform photosynthesis.