Final answer:
Lipoproteins indeed dissolve in the bloodstream, allowing the transportation of hydrophobic lipids through the blood. They are categorized by their density and each type has specific roles in lipid transport and metabolism.
Step-by-step explanation:
The statement that lipoproteins dissolve in the bloodstream is true. Lipoproteins are lipid-protein complexes essential for transporting lipids, which are hydrophobic, across the hydrophilic environment of the bloodstream. Without lipoproteins, lipids like cholesterol and triglycerides could not travel through the blood to reach various tissues where they are needed.
Lipoproteins vary in density, with each type playing a distinct role in lipid transport. Very low-density lipoproteins (VLDL) transport triglycerides from the liver to tissues. Intermediate-density lipoproteins (IDL) are transformation products of VLDL and carry a mix of fats and cholesterol to the liver. Low-density lipoproteins (LDL), which are sometimes called "bad cholesterol", deliver cholesterol throughout the body. Conversely, high-density lipoproteins (HDL), known as "good cholesterol", help remove cholesterol from the bloodstream, taking it back to the liver for reuse or excretion.