Which of the following are considered essential nutrients for organisms?

Essential nutrients are compounds that an organism cannot synthesize on its own and must obtain from its environment in order to survive and thrive. In the context of essential nutrients, phosphorus, sulfur, and iron are often categorized as macronutrients and micronutrients critical for various biological processes.

Phosphorus is key for the formation of DNA, RNA, and ATP, which are vital for genetic information storage and energy transfer. Sulfur is important for synthesizing certain amino acids and vitamins, contributing to the structure and function of proteins. Iron plays a critical role in the formation of hemoglobin and is essential for oxygen transport in blood as well as a cofactor for various enzymes.

In contrast, amino acids and vitamins can be considered essential nutrients, but they primarily serve specific roles and can sometimes be synthesized in certain organisms, depending on their metabolic capabilities. Glucose and fructose, while important carbohydrates that organisms use as energy sources, are not categorized as essential nutrients since many organisms can produce them through metabolic pathways. Protein and lipids serve as structural and functional components in cells; however, they are composed of smaller, essential building blocks (like amino acids and fatty acids) that must be obtained from the diet.

Thus, phosphorus, sulfur, and iron are rightly identified