Final answer:
the generation of new cells to replace cells that are lost or to grow new tissue occurs by the
process of cell division.
Step-by-step explanation:
The generation of new cells to replace cells that are lost or to grow new tissue occurs by the process of cell division. This process is essential not only for the growth and development of a multicellular organism from a single fertilized egg, or zygote, but also for the maintenance and repair of tissues throughout an organism's life. For instance, new blood and skin cells are constantly being produced to replace those that have been damaged or have reached the end of their life cycle.
Stem cell research aims to harness the unique ability of stem cells to divide and differentiate into various cell types in order to regenerate and repair cellular damage. Stem cells are crucial because they provide the body with the ability to renew and repair tissues, especially as adult cells lose their ability to divide and heal themselves over time due to aging or injury.
In summary, cell division is the critical biological process responsible for growth, repair, and maintenance in both single-celled and multicellular organisms, including humans.