Our body contains about 70% water so most abundant molecule is H2O.
No, water is the most abundant molecule in the body.
Water is the most abundant molecule in just about any part of them body, including the brain.
Water is the most abundant molecule on Earth's surface. It is also the most abundant molecule found in the human body. Water helps deliver oxygen and nutrients to different parts of the body and removes toxins and wastes from the body. It also helps to regulate body temperature and acts as a cushion to protect internal organs and joints.
Triglycerides
The question is flawed. Substance can mean element or molecule. I'll go with molecule since organic simply means carbon atoms are present. Hydrogen dioxide is the most abundant inorganic "substance".
Human chromosome #1 contains the largest single molecule in the human body. It is one very long molecule of DNA. The DNA is wrapped around molecules of proteins called histones (shaped somewhat like spools) to protect it and provide strength.
Water (H20) and Carbon, for the most part, but there's also traces of other smaller minerals, such as calcium and magnesium.
water
DNA
Water
water
Water or H2O