Yolk sac in the embryo of human female is non functional. Give reason.

Explanation

**Step-by-Step Solution:**

1. **Understanding Yolk Sac Functionality**: The yolk sac is an extra-embryonic structure that is typically involved in providing nutrients to the developing embryo in many species, particularly those that undergo oviparity (egg-laying).

2. **Human Development Type**: Humans exhibit viviparity, which means that the embryo develops inside the mother's body rather than in an egg outside. This internal development is crucial for the nourishment and protection of the embryo.

3. **Role of the Placenta**: In humans, the placenta is formed during pregnancy. It serves as the interface between the mother and the developing embryo, facilitating the exchange of nutrients, gases, and waste products. The placenta effectively takes over the functions that a yolk sac would typically provide in oviparous organisms.

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