Why are microbial genes considered vital for physiology?

Microbial genes are considered vital for physiology primarily because they outnumber human genes and play a multitude of roles in health. The human body is home to trillions of microbes, collectively referred to as the microbiome, which have a significant influence on various physiological processes. These genes from microorganisms can participate in digestion, synthesis of essential vitamins, and modulation of the immune system, contributing to overall health and well-being.

In contrast, options that focus solely on diseases or the lack of connection to human cells do not encapsulate the broader and essential roles these microbial genes play. Moreover, while insights into genetic diseases are important, they do not directly address the vital contributions of microbial genes to human physiology, which is more comprehensive in context. Hence, the choice that emphasizes the abundance and versatile functions of microbial genes accurately reflects their essential nature in human health.