Final answer:
The embryo being directly enclosed in and protected by the amnion is true. The amnion provides a safe environment for the developing embryo, protecting it from physical harm and temperature changes while allowing it to move and develop important prenatal functions.
Step-by-step explanation:
The statement that the embryo is directly enclosed in and protected by the amnion is true. The amnion is a thin but robust membrane that contains amniotic fluid, forming a protective sac around the embryo. This fluid-filled cavity provides a buffered environment that safeguards the embryo from physical trauma and temperature fluctuations. During development, the amniotic sac allows the embryo to move freely and practice essential actions such as swallowing and breathing movements, which are vital for fetal development outside of the womb.
In addition to the amnion, the chorion is another membrane that encases the amnion itself. This membranous layer plays a role in the gas exchange which is necessary for the embryo's survival. Ultimately, the amniotic egg structure, including the amnion and chorion among other components like the allantois and yolk sac, represents an evolutionary milestone that enabled vertebrates to successfully reproduce outside of aquatic environments, thus colonizing a variety of terrestrial habitats.