Which of the following molecules is not absorbed into the bloodstream due to its low solubility in water?

• A. Vitamin C
• B. Cholesterol
• C. Glucose
• D. Ethanol

Answer: (B)

Verified step by step guidance

1. Step 1: Understand the concept of solubility in water. Solubility refers to the ability of a substance to dissolve in a solvent, such as water. Molecules that are polar or have hydrogen bonding capabilities tend to be more soluble in water.
2. Step 2: Analyze the molecular structure of each compound. Vitamin C, glucose, and ethanol all have polar functional groups that can form hydrogen bonds with water, increasing their solubility.
3. Step 3: Consider cholesterol's structure. Cholesterol is a large, non-polar molecule with a hydrophobic steroid backbone, making it less soluble in water compared to the other molecules listed.
4. Step 4: Relate solubility to absorption into the bloodstream. Molecules that are soluble in water can be absorbed more easily into the bloodstream, as they can dissolve in the aqueous environment of the body.
5. Step 5: Conclude that cholesterol, due to its low solubility in water, is not absorbed into the bloodstream as efficiently as the other molecules listed.