Which macromolecule is the main component of muscle tissue and contains nitrogen?

• A. Proteins
• B. Carbohydrates
• C. Lipids
• D. Nucleic Acids

Answer: (A)

Proteins are the main components of muscle tissue, built from amino acids that include nitrogen in their structure (the amino group). This nitrogen makes proteins distinct from other macromolecules. In muscles, structural and contractile proteins like actin and myosin provide both support and the ability to contract, which is why muscles are so protein-rich.

Carbohydrates are primarily energy sources and are made of carbon, hydrogen, and oxygen with little nitrogen. Lipids store energy and form membranes, mainly consisting of carbon, hydrogen, and oxygen (sometimes phosphorus), with no nitrogen in their basic makeup. Nucleic acids contain nitrogen in their bases, but they are not the bulk of muscle tissue; they’re involved in genetic information and directing protein synthesis, not forming the main tissue structure itself.

So, the macromolecule that both makes up most of muscle tissue and contains nitrogen is proteins.