Which of these is mismatched? a. chorion-sense perception b. yolk sac-first site of blood cell formation c. allantois- -umbilical blood vessels d. amnion-contains fluid that protects embryo

The first step is to understand the functions of each term mentioned in the exercise in the context of embryonic development: 1. Chorion: It is the outermost membrane of the embryo, which contributes to the formation of the placenta and regulates gas exchange between the embryo and the outside environment. 2. Yolk sac: It is an extra-embryonic membrane that provides initial nourishment for the embryo and is the first site of blood cell formation in the developing embryo. 3. Allantois: It forms a part of the umbilical cord and helps in waste removal and gas exchange in the developing embryo. It eventually forms the umbilical blood vessels. 4. Amnion: It is a thin membrane surrounding the embryo and contains amniotic fluid, which cushions and protects the embryo from mechanical injuries.

Now, we need to evaluate each option and determine if the functions mentioned match with the provided terms: a. chorion-sense perception: This option is not correct because the primary function of the chorion is not related to sense perception but the formation of the placenta and gas exchange. b. yolk sac-first site of blood cell formation: This option is correct, as the yolk sac indeed serves as the first site of blood cell formation in the developing embryo. c. allantois- -umbilical blood vessels: This option is also correct, as the allantois eventually forms the umbilical blood vessels responsible for waste removal and gas exchange in the embryo. d. amnion-contains fluid that protects the embryo: This option is correct, as the amnion membrane contains the amniotic fluid, which cushions and protects the embryo during development.

Based on the analysis above, option (a) chorion-sense perception is the mismatched option, as the primary function of the chorion is not related to sense perception but the formation of the placenta and gas exchange.