Which of the following statement is correct about blood?

• A. Hemoglobin in the red blood cells binds to O₂ but not to CO₂.
• B. Platelets play an important role in blood clotting.
• C. White blood cells are the smallest of the formed elements.
• D. Plasma constitutes about half of the blood and is mostly protein.

Answer: (B)

Verified step by step guidance

1. Step 1: Understand the components of blood. Blood consists of formed elements (red blood cells, white blood cells, and platelets) and plasma, which is the liquid portion.
2. Step 2: Analyze the role of hemoglobin. Hemoglobin in red blood cells primarily binds to oxygen (O\_2) for transport, but carbon dioxide (CO\_2) is mostly transported dissolved in plasma or bound to other molecules, not primarily by hemoglobin.
3. Step 3: Evaluate the function of platelets. Platelets are small cell fragments that play a crucial role in blood clotting by aggregating at injury sites to form clots and prevent bleeding.
4. Step 4: Compare sizes of formed elements. Among the formed elements, white blood cells are generally larger than red blood cells and platelets, so they are not the smallest.
5. Step 5: Consider plasma composition. Plasma makes up about 55% of blood volume and is mostly water, with proteins constituting a smaller portion, not about half.