Because a hen's whole egg is a cell, which you call yolk.
hope it helps
Tirtha Yeole
legends group

Understanding the Hen's Egg
The hen's egg is a fascinating biological structure that plays a crucial role in reproduction and development. Let's break down why it is classified as a cell.
What is a Cell?
- A cell is the basic unit of life, the smallest structural and functional unit of an organism.
- Cells can exist independently (like bacteria) or as part of multicellular organisms (like plants and animals).
Structure of a Hen's Egg
- The hen's egg is primarily composed of several parts, including:
- Yolk: The nutrient-rich part that nourishes the developing embryo.
- Albumen (Egg White): Provides additional protection and nutrients.
- Shell Membrane: Protects the contents of the egg.
- Shell: The hard outer covering made primarily of calcium carbonate, providing protection.
Why is it Considered a Cell?
- The hen's egg is considered a single cell, known as an oocyte, which is specialized for reproduction.
- It contains all the necessary components for the development of a new organism, including genetic material (DNA) within the yolk.
- When fertilized by a sperm, the egg begins the process of cell division, leading to the development of the chick.
Conclusion
In summary, while a hen's egg may appear large and complex, it is fundamentally a single cell designed for the purpose of reproduction. This classification helps us understand the biological processes that lead to new life in birds.