Question

a scientist is examining the role of an element found in fats and carbohydrates of living things. this element makes up 65% of human body mass. which statement describes the element he is studying? he is studying oxygen, which can also be found in proteins. he is studying oxygen, which is the most abundant element in the atmosphere. he is studying nitrogen, which can also be found in proteins. he is studying nitrogen, which is the most abundant element in the atmosphere.

Explanation:

1. Recall the composition of fats, carbohydrates, and proteins, and the abundance of elements in the human body and atmosphere:

• Fats and carbohydrates contain carbon, hydrogen, and oxygen. Oxygen makes up about 65% of human body mass. Proteins also contain oxygen (along with C, H, N, etc.).
• The most abundant element in the atmosphere is nitrogen (about 78%), not oxygen. Nitrogen is in proteins but not a major component of fats/carbohydrates in the same way as oxygen, and nitrogen is not 65% of body mass.

1. Analyze each option:

• Option 1: Oxygen is in fats, carbs, and proteins, and ~65% of body mass. Correct.
• Option 2: Oxygen is not the most abundant in the atmosphere (nitrogen is). Incorrect.
• Option 3: Nitrogen is in proteins but not a main element of fats/carbohydrates, and not 65% of body mass. Incorrect.
• Option 4: Nitrogen is most abundant in atmosphere, but the element in fats/carbs (and 65% body mass) is oxygen. Incorrect.

Answer:

He is studying oxygen, which can also be found in proteins.