Final answer:
The majority of human blood by volume is plasma, which makes up about 55% and is majorly composed of water and proteins.
Step-by-step explanation:
By volume, the majority of human whole blood is composed of plasma, which constitutes about 55% of blood by volume. Plasma itself is primarily made up of water, with approximately 92% of plasma consisting of it. The remainder of plasma contains a variety of dissolved substances, including a significant amount of proteins, as well as glucose, mineral ions, hormones, carbon dioxide, and other vital compounds.