Question

According to the passage, when biologists believed that the cells in the early embryo were undetermined, they made which of the following mistakes?

• A. They did not realize that there was a connection between the issue of cell determination and the outcome of the separation experiment
• B. They assumed that the results of experiments on embryos did not depend on the particular animal species used for such experiments
• C. They assumed that it was crucial to perform the separation experiment at an early stage in the embryo’s life
• D. They assumed that different ways of separating an embryo into two parts would be equivalent as far as the fate of the two parts was concerned

Answer 1

The correct option is D They assumed that different ways of separating an embryo into two parts would be equivalent as far as the fate of the two parts was concerned

D is the best answer. According to the author, early investigators arrived at the conclusion that the cells of the embryo are undetermined because they “found that if they separated an invertebrate animal embryo into two parts at an early stage of its life, it would survive and develop as two normal embryos” (lines 1-6). However, later biologists discovered that when an embryo was cut in places different from the one used by the early investigators, it did not form two whole embryos. Because the earlier biologists apparently arrived at their conclusion without attempting to cut an embryo in different planes, it would appear that they assumed, erroneously, that different ways of separating the embryos would not affect the fate of the two embryo parts.