Final answer:
Gregor Mendel concluded traits are controlled by discrete units inherited in pairs and introduced the concept of dominant traits, demonstrated via monohybrid crosses of purebred pea plants.
Step-by-step explanation:
Gregor Mendel drew the conclusion that traits are controlled by discrete units that are inherited in pairs, with one unit coming from each parent. He deduced that these units, which we now know as genes, could exist in different forms, which are responsible for the variations in traits seen in offspring. Mendel called the observed trait ‘dominant’ if it appeared in the first-generation (F1) offspring when one parent had it in pure form.
In his monohybrid crosses, Mendel used purebred pea plants with differing characteristics to determine patterns of inheritance. When he crossed plants that differed in a single trait, such as tall and dwarf height, all offspring were tall, demonstrating the principle of dominance. This principle was one of the key concepts leading to the formulation of Mendel's laws of inheritance, laying the foundation for modern genetics. Mendel’s work with pea plants enabled him to conclude the predictability of inheritance patterns, which became instrumental in the study of heredity.