Final answer:
Excessive or insufficient growth hormone in humans can lead to conditions such as pituitary dwarfism, gigantism, or acromegaly, affecting symmetrical body formation and causing either reduced or excessive growth. In plants, both deficiencies and excesses in factors like water, light, and nutrients can limit growth or lead to toxicity.
Step-by-step explanation:
Both excessive and insufficient amounts of growth hormone (GH) can cause significant health issues. In children, an underproduction of GH leads to pituitary dwarfism, characterized by a symmetric body but significantly reduced growth, potentially with heights under 30 inches.
Conversely, an oversecretion of GH can result in gigantism, where children can grow to be over eight feet tall due to excessive growth. In adults, too much GH does not lead to increased height but causes acromegaly, a condition marked by the enlargement of the bones in the face, hands, and feet. When discussing plants, the factors that regulate growth can lead to similar issues of under or over development.
Too little water, light, or nutrients can stunt plant growth, while too much can actually be toxic and reduce growth. The concept of saturation is essential to understand, as there is a point where increased levels of the growth-regulating factor no longer enhance growth, and further increases can be detrimental.