International Sports Sciences Association (ISSA) Trainer Practice Exam

About what percentage of the human body is composed of the six key elements: oxygen, carbon, hydrogen, nitrogen, calcium, and phosphorous?

1. 85%

2. 90%

3. 98%

4. 100%

The correct answer is: 98%

The answer indicates that approximately 98% of the human body is composed of the six key elements: oxygen, carbon, hydrogen, nitrogen, calcium, and phosphorus. This is correct because these six elements play critical roles in the body’s structure and function. Oxygen is essential for cellular respiration, helping to produce energy in the form of ATP. Carbon is a fundamental building block of life, forming the backbone of organic molecules such as proteins, fats, and carbohydrates. Hydrogen is involved in numerous biochemical reactions and is a component of water, which is vital for life. Nitrogen is a key element in amino acids and nucleic acids, which are critical for the structure and function of proteins and genetic material, respectively. Calcium is crucial for bone structure and various biological processes such as muscle contraction and neurotransmission. Lastly, phosphorus is important for energy transfer and storage, as well as being a key component of DNA and RNA. While the percentages for options around 85% and 90% are substantial, they fall short of encompassing the vast majority of the body's composition. The option indicating 100% is inaccurate as there are trace elements present in the human body that do not fall within these six major elements. Therefore, stating that about 98%