Question

p53 can trigger apoptosis if certain cell-cycle events fail. How does this regulatory outcome benefit a multicellular organism?

Short answer

The apoptosis triggered by p53 helps as a tumor-suppressive factor by preventing the production of defective proteins due to damaged DNA.

Step-by-step solution

Functions of p53 and apoptosis

P53 is a tumor suppressor gene that promotes the process of apoptosis in which the cells are made to die in an organised way due to the defective DNA that they might have. The process of apoptosis is a natural way that assists in eliminating unwanted and damaged cells beyond repair. Importantly, the p53 gene is the one that initiates such a process of eliminating the unwanted damaged cells.

Reasoning 

For instance, let us take a cell that consists of defective DNA that results in the production of defective proteins. Being the condition that the parent cell has defective DNA, the daughter cells that originate from the parent cell would also produce a similar condition of defective proteins. Eventually, there might be the production of cancerous proteins at last due to the defective condition (mutation), and that may result in cancerous tumors. So, the tumor suppressor gene p53 intervenes and orders for the death of such cells in order to avoid adverse conditions. Therefore, the gene, through a regulatory mechanism, helps in the prevention of the development of tumors in the body.

Disregarding other views

As the function of the p53 gene is to suppress the development of tumours that arise due to some defective events in the body, it helps in the prevention of the development of cancerous tumours by triggering the process of apoptosis. Therefore, no other primary benefit could be extracted from that gene preferably.