In the context of specialized connective tissue, blood is best classified as what type of mixture?

• A. A pure substance (a single element)
• B. A heterogeneous mixture (a suspension of formed elements in plasma)
• C. A homogeneous mixture (a true solution)
• D. A colloid with no suspended particles

Answer: (B)

Verified step by step guidance

1. Understand the components of blood: blood consists of formed elements (such as red blood cells, white blood cells, and platelets) suspended in plasma, which is a liquid matrix.
2. Recall the definitions of mixture types: a pure substance contains only one type of element or compound; a homogeneous mixture (true solution) has uniform composition throughout; a heterogeneous mixture has visibly different components or phases; a colloid contains particles that are intermediate in size and do not settle out.
3. Analyze blood's characteristics: since blood contains cells suspended in plasma, these formed elements can settle out if left undisturbed, indicating it is not a true solution or pure substance.
4. Recognize that blood is a suspension because the formed elements are suspended in plasma and can be separated by centrifugation, which fits the definition of a heterogeneous mixture.
5. Conclude that blood is best classified as a heterogeneous mixture (a suspension of formed elements in plasma) based on its composition and behavior.