Final answer:
Corn plants exhibit a range of heights due to polygenic inheritance and environmental influences, resulting in continuous phenotypic variation.
Step-by-step explanation:
The reason why corn plants cannot be separated into discrete types or classes based on their height is that height in corn plants is controlled by multiple genes with continuous variation. Unlike Mendel's pea plants, characteristics such as height in corn do not adhere to simple dominance-recessive genetic patterns. Instead, they exhibit what's known as polygenic inheritance, where multiple genes contribute to the expression of a single trait, resulting in a gradient of physical appearances rather than distinct classes. Factors such as the amount of water or use of fertilizer can also influence the height of corn plants, further contributing to the variation seen in corn populations.
Mendel's original work with peas demonstrated a very straightforward form of inheritance with discrete characteristics—peas were either tall or short. However, with many traits such as height in humans or corn, multiple genetic factors are involved, leading to a continuous spectrum of possible phenotypes. This is further complicated by environmental factors such as nutrition and water availability, which can greatly affect the growth of plants.
Corn height is due to polygenic inheritance and environmental factors, leading to a continuous variation in plant heights.