In an introduction to blood, what are the two major components of blood?

• A. Serum and platelets
• B. Hemoglobin and plasma proteins
• C. Erythrocytes and leukocytes
• D. Plasma and formed elements

Answer: (D)

Verified step by step guidance

1. Understand that blood is a connective tissue composed of both liquid and cellular parts.
2. Identify that the liquid portion of blood is called plasma, which contains water, salts, proteins, and other dissolved substances.
3. Recognize that the cellular portion, known as formed elements, includes erythrocytes (red blood cells), leukocytes (white blood cells), and platelets.
4. Note that the two major components of blood are therefore plasma (the fluid matrix) and formed elements (the cells and cell fragments).
5. Eliminate other options by understanding that serum is plasma without clotting factors, hemoglobin is a protein inside red blood cells, and erythrocytes and leukocytes are only part of the formed elements, not the entire blood composition.