The chemical element represented by 'K' is potassium. Potassium is an alkali metal and is known for its high reactivity, particularly with water, which produces hydrogen gas and a corresponding alkaline solution. This element plays essential roles in biological systems, particularly in nerve signal transmission and muscle contraction in humans and other living organisms. In agriculture, potassium is vital as a nutrient for plants, contributing to overall plant health and growth. It is commonly found in fertilizers to support crop yields, highlighting its importance in both health and food production.