Difficulty: Easy
Correct Answer: Water
Explanation:
Introduction / Context:
The human body is made up of various components, including water, proteins, fats, carbohydrates, and minerals. Each plays a different role in structure and metabolism. A common general knowledge question in biology and health science asks which of these components contributes the largest fraction to total body weight. Understanding this helps explain why hydration is so important and why body composition is often discussed in terms of water content.
Given Data / Assumptions:
Concept / Approach:
In an average adult, water makes up about 60 to 70 percent of total body weight, though the exact figure varies with age, sex, and body composition. Proteins, fats, minerals, and carbohydrates make up the remaining mass. Fats are more variable depending on body fat percentage but typically contribute less mass than water. Proteins form structural components of muscles and organs and account for a significant but smaller portion than water. Carbohydrates represent only a small fraction of body weight because they are stored in limited amounts as glycogen. Minerals such as calcium and phosphorus are important in bones and teeth but also represent a smaller percentage compared with water. Therefore, water is the single largest component by mass.
Step-by-Step Solution:
Step 1: Recall that the human body is often described as being about two-thirds water by weight.
Step 2: Recognise that water is present inside cells (intracellular fluid), outside cells (extracellular fluid), in blood, lymph, and other bodily fluids.
Step 3: Understand that although fats are energy dense, their proportion by mass is usually lower than the proportion of water in all but extremely obese individuals.
Step 4: Note that proteins and minerals are essential for structure and function but together still do not surpass water in total mass.
Step 5: Observe that carbohydrates contribute only a small fraction of body weight because they are not stored in large quantities.
Step 6: Conclude that water is the nutrient forming the greatest share of body weight.
Verification / Alternative check:
Typical body composition data for a 70 kilogram adult might show approximately 42 liters of water (about 60 percent of total weight), 12 kilograms of fat (around 17 percent), 10 kilograms of protein, and smaller amounts of minerals and carbohydrates. These figures vary, but across many examples, water remains the predominant component by mass. Clinical discussions about dehydration and fluid balance further emphasise the central importance of water to body weight and function, confirming that water is the correct answer.
Why Other Options Are Wrong:
Option B: Fats (lipids) provide concentrated energy and can form a large store, but in average individuals they do not exceed water as a percentage of body mass.
Option C: Carbohydrates are stored mainly as glycogen in liver and muscles and make up only a small fraction of body weight.
Option D: Proteins are crucial for structure and enzymes, but their total mass is generally less than that of water in the body.
Option E: Minerals such as calcium and phosphorus are important in bones and teeth, yet they account for a relatively small proportion of total body weight compared with water.
Common Pitfalls:
Some learners may assume that fats must dominate body mass because of discussions about obesity and weight gain, forgetting that lean tissues and fluids are mostly water. Others confuse energy content with mass, assuming that because fats yield more kilocalories per gram, they must be the largest component by weight. To avoid such errors, remember that the human body is often described as being mostly water, and this simple phrase reflects real body composition data.
Final Answer:
Among the major nutrients, water forms the greatest proportion of our total body weight by mass.
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