Which component of blood makes up approximately 55 percent of the blood volume?

• A. Red blood cells
• B. Platelets
• C. White blood cells
• D. Plasma

Answer: (D)

Verified step by step guidance

1. Understand the composition of blood: Blood is composed of plasma and formed elements, which include red blood cells, white blood cells, and platelets.
2. Recognize that plasma is the liquid portion of blood, which serves as a medium for transporting nutrients, hormones, and waste products.
3. Recall that plasma is primarily made up of water (about 90%), but also contains proteins, glucose, electrolytes, and other dissolved substances.
4. Identify that the formed elements (red blood cells, white blood cells, and platelets) make up the remaining 45% of blood volume.
5. Conclude that since plasma makes up the majority of the blood volume, it accounts for approximately 55% of the total blood volume.