Question on bio, please help.

[Lilith]

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Hi!Which of the following is involved in respiration and excretion, and develops into the placenta in humans?

Chorion or
Allantios

Kaplan says it's allantois, but I thought allantois becomes the umbillical cord, which connects the embryo to the placenta. Chorion actually fused with the maternal tissue and becomes "part of the placenta." What do you think? Thanks.

 

[coodoo]

The chorion lines the inner surface of the shell (which is permeable to gases) and participates in the exchange of O2 and CO2 between the embryo and the outside air.
The allantois stores metabolic wastes (chiefly uric acid) of the embryo and, as it grows larger, also participates in gas exchange.

 

[Lilith]

Thanks, Coodoo. In case of placental animals, these parts have different functions right?