Answer;
The amnion
Explanation;
-The amnion is a tough, thin membrane that surrounds a developing fetus in mammals, reptiles, and birds. It is the first of the three cavities (amnion, chorion and yolk sac) in the embryo and is formed on 8 dpc.
-In the human body, the amnion is the first of three cavities, including the chorion and yolk sac, that work together to keep the developing fetus nourished and protected.
-The amnion provides a protective environment in which the fetus' temperature is regulated and protects the fetus from friction caused by the mother's movements.
Answer: Possession of Valves
Explanation: Veins possess valves which ensures that blood flows in only one direction. Valves helps blood to flow back to the heart against gravitational force.
Arteries don't have valves because the pressure originating from the heart is capable of causing the blood to flow in one direction.
When the structure and function of an organism adjusts to its environment it is adapting.
You would from the scapula in the forelimb part of the body