Final answer:
Probability in genetics is primarily expressed in fractions and percentages, which represent the likelihood of specific genetic events occurring, and these are fundamental concepts in the field of Mendelian genetics.
Step-by-step explanation:
Genetic probability quantifies the chance that a particular genetic event will occur. This is an essential concept in Mendelian genetics, where the likelihood of inheriting certain traits is predicted based on these probabilities. The classic Mendelian ratios, such as the 9:3:3:1 phenotypic ratio seen in dihybrid crosses, exemplify probabilities expressed as fractions. These probabilities inform us about the expected frequency of a phenotype in a large number of offspring. Moreover, the probability can also be expressed in percentages for practical understanding; for example, a 75% chance indicates that a certain phenotype is quite likely to occur. In some cases, especially for simple monohybrid crosses involving complete dominance, probabilities can even be expressed as whole numbers, signifying certainty, such as 1 (or 100%), which represents a guaranteed occurrence of a phenotype.
Understanding these concepts helps in predicting genetic outcomes and appreciates the role of chance and law of probability in the transmission of hereditary characteristics.