What are the two types of cells primarily discussed in biology?

The primary distinction in cell biology is between prokaryotic and eukaryotic cells. Prokaryotic cells are simpler and smaller, lacking a nucleus and membrane-bound organelles. They are typically unicellular organisms, like bacteria. In contrast, eukaryotic cells are more complex, possessing a true nucleus and various organelles that perform specific functions. Eukaryotic cells can be part of unicellular or multicellular organisms, including plants, animals, and fungi.

This classification is fundamental to understanding the diverse forms of life on Earth and their cellular structures. While the other options mention important types of cells, they are subsets of the larger categories defined by prokaryotic and eukaryotic cells. For example, red and white blood cells are specialized eukaryotic cells found in animals, and both stem cells and germ cells are also parts of eukaryotic biology. Similarly, plant and animal cells represent specific types of eukaryotic cells. Thus, the distinction between prokaryotic and eukaryotic cells serves as a foundational concept in biology.