Final answer:
Plasma accounts for about 55 percent of blood by volume, and is mainly composed of water (92 percent), along with plasma proteins, organic and inorganic substances that support various bodily functions.
Step-by-step explanation:
Plasma makes up about 55 percent of blood by volume, which is more than half of our blood content. Its composition is crucial as it carries many important substances needed for the body's function. Plasma is composed of about 92 percent water, with the rest being a mixture of plasma proteins, organic constituents like glucose, amino acids, fatty acids, urea, cholesterol, and inorganic constituents such as phosphates, potassium (K), sodium (Na), chloride (Cl), and iron (Fe). These components of plasma play significant roles in transporting nutrients, hormones, and waste products throughout the body.