Where are microvilli typically found?

• A. In places where absorption occurs
• B. In the cell's nucleus
• C. In mitochondria
• D. In the endoplasmic reticulum

Answer: (A)

Microvilli are tiny projections of the cell’s plasma membrane that dramatically increase surface area, making absorption more efficient. They’re most prominent on absorptive cells, such as those lining the small intestine and the proximal tubules of the kidney, where nutrients and ions need to be taken up quickly. The brush border of the intestinal lining is essentially a cluster of microvilli, and their membranes host enzymes that assist digestion right at the point of contact. They are supported by a core of actin filaments and are not intracellular organelles like the nucleus, mitochondria, or endoplasmic reticulum, which explains why their primary role is to expand the surface area for absorption rather than to act as separate, enclosed structures inside the cell.