Sperm and eggs are not alive, the do not individually possess the key characteristics of living organisms. They do not develop or grow (they are in their final form so to speak), they do not reproduce (an egg can not replicate itself to create an identical egg, sperm does not replicate itself to create more sperm), and they are in a state of meiotic and metabolic dormancy, to name a few.

Sperm and eggs are indeed cells and thus biologically alive in the sense that they possess cellular structures and metabolic activity, but they do not fulfill all criteria typically used to define an independent living organism. For example, they do not grow or develop further once mature, nor do they reproduce by themselves (no mitotic division to create more gametes).

Both gametes are haploid cells produced by meiosis and exist in a state of metabolic dormancy or reduced activity until fertilization occurs. This dormancy means their metabolic processes are limited compared to somatic cells.

Upon fertilization, the egg is activated to begin development, which supports the idea that individually, sperm and eggs are not complete organisms but rather specialized reproductive cells.

Sources emphasize that sperm can survive for limited times outside the body or within the female reproductive tract but will die without fertilization, indicating they are alive but transient.

There is some debate in popular and scientific discussions about whether gametes should be classified as 'alive' in the same way as independent organisms; however, mainstream biology classifies them as living cells with specialized functions rather than autonomous organisms.