Question

Why are the results of genetic crosses shown in punnett squares interpreted as probabilities, not certainties? give some specific reasons?

Answer 1

The explanation of the fact that the distribution is a probability and not a certainty is that it is a phenomenon that is not matrisable due to the random crossing of individuals (panmixia) and gametes of two given individuals (pangamia).

Panmixia (random crossings between individuals) covers:

* Equiprobability of gametes: "pangamia" (panmixia of gametes)

* Gamete encounter at random or random formation of couples (Panmixia)

* Random segregation of gametes during meiosis

In other words, it is considered that there is no pre-zygotic selection, the gametes of all the individuals of the generation considered being pooled. The formation of the next generation is therefore the product of a random draw in this gametic pool.

Answer 2

I believe this is because the types of offspring produced by any genetic crosses depends on chance such that there is no certainty of getting a particular trait. For instance, the number of gametes produced that contain particular alleles depends on chance and it is not certain. Likewise, the fusion of two gametes with particular alleles is not certain. Therefore, the outcomes of genetic crosses shown in Punnet squares are just probable or possible outcomes.