Firstly, when working with garden peas, he used plants that belonged to different varieties for crossbreeding. So, for example, one grade of pea was always yellow, and the other was always green. Since peas are a self-pollinated plant, under natural conditions, these varieties do not mix. Such varieties are called clean lines.
Secondly, in order to get more material for the analysis of the laws of heredity, Mendel worked not with one, but with several parental pairs of peas.
Third, Mendel deliberately simplified the task by observing the inheritance of not all the traits of peas at once, but only of one pair of them. For his experiments, he initially chose the color of pea seeds – peas. In cases where the parental organisms differ by only one feature (for example, only by the color of the seeds or only by the shape of the seeds), crossbreeding is called monohybrid.
Fourth, having a mathematical education, Mendel applied quantitative methods for data processing: he not only noticed what color the seeds of peas were from offspring, but also accurately calculated how many such seeds appeared.
Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.