Why is cell division essential for the growth of multicellular organisms?

Cell division is fundamentally important for the growth of multicellular organisms primarily because it allows for development from a single fertilized egg. Through the process of cell division, one fertilized egg undergoes numerous rounds of division to produce a vast number of cells that will differentiate and specialize, contributing to the formation of various tissues and organs in the organism. This process, known as embryogenesis, is crucial as it establishes the foundational structure of the organism and enables it to grow in size and complexity.

While other aspects of growth, such as replacing older cells and absorbing nutrients, are important, they are secondary to the initial formation and development of an organism from a single zygote. Cell division facilitates the transition from the simplest form of life into a fully developed multicellular entity, allowing for organized tissue development, which is essential for the functioning of higher organisms.