IMAT Biology Practice Exam 2026 - Free IMAT Biology Practice Questions and Study Guide

Stem cells are defined by two abilities: to stay as stem cells through self-renewal and to give rise to specialized cell types through differentiation. Self-renewal means that when a stem cell divides, at least one daughter cell remains undifferentiated to replenish the stem cell pool. Differentiation lets the lineage produce the various cell types needed for growth, development, and tissue repair. Because tissues need both a reservoir of undifferentiated cells and the ability to replace mature cells, stem cells can both self-renew and differentiate. If they could only differentiate, the stem cell pool would diminish over time and tissue maintenance would fail. If they could only self-renew, there would be plenty of undifferentiated cells but no new specialized cells to replace damaged or aging cells. So the best answer reflects both capabilities.