OCR GCSE Biology Practice Exam 2026 – Comprehensive All-in-One Guide to Exam Success

Humans cannot regenerate limbs like newts primarily because human stem cells are specialized. In newts, stem cells retain a more potent ability to differentiate into various cell types, which is essential for regeneration. When a newt loses a limb, these stem cells are able to proliferate and then differentiate into the specific types of tissues needed to form a new limb, including muscle, bone, and skin.

In contrast, human stem cells, while they do exist, are more specialized and limited in their capabilities. They are often involved in repair and maintenance of existing tissues rather than forming entirely new structures like limbs. This limitation in regenerative capacity is due to the complex structure and requirements of human limbs, including the need for specific types of cells to work in harmony, which is not something that human cells can achieve easily after a significant injury.

This understanding highlights the fascinating differences in regeneration capabilities across species and illustrates the adaptive evolution of organisms in response to their environments.