The muscles, tissues, and blood all are made-up of:

The correct answer is Proteins because proteins serve as the fundamental structural building blocks required to assemble, maintain, and repair human cells and tissues.

• Step 1 (Structural Biology): Proteins are complex molecules built out of long chains of amino acids. Muscle fibers are comprised of structural proteins like actin and myosin, while blood components rely heavily on proteins like hemoglobin (to carry oxygen) and albumin.
• Incorrect Options:
  • Carbohydrates is incorrect because carbohydrates function primarily as short-term energy fuel for cells rather than serving as structural tissue building blocks.
  • Vitamins is incorrect because vitamins are organic micro-nutrients required in small concentrations to regulate metabolic pathways, rather than forming physical tissue structures.
  • Fats is incorrect because fats (lipids) are utilized for long-term energy storage, cell membrane boundaries, and insulation rather than constructing muscle masses.