Probability in Genetics

This explains the predicted ratio or chances of having a particular trait or character in a cross or transmission from generation to another. This explains the predicted ratio of 3:1 for monohybrid cross and 9:3:3:1 for dihybrid cross.


Probability is usually expressed in units ranging from 0-1. Two principles are necessary is understand the importance or probability in genetics.

  1. The result of one

trial of a chanced event does not affect the result of latter traits of the event

  1. The chance that two independent events will occur together simultaneously is the product of their chances of occurring separate question

In a plant of genotype Tt, what is the probability that a gamete will contain gene t?


Question (Use the comment box to answer for evaluation and discussion)

An albino man marries a normal woman (homozygous) for skin pigmentation). What is the probability the couple could have an albino child?

Gene for albinism = aa

Gene for the Normal pigmentation = AA

 (1) In a cross involving a heterozygous red flowered plant (Rr) and a white flowered plant (rr), what is the probability that the offspring will be (Rr)?

  1. What is the probability that two consecutive children of the same parent will be males?
  2. In human beings, the albino trait is recessive is the probability of parents who are heterozygous for albinism having an albino child?

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