Question

It can be inferred from the passage that the morphogenetic determinants present in the early embryo are:

• A. evenly distributed unless the embryo is not developing normally
• B. inactive until the embryo cells become irreversibly committed to their final function
• C. identical to those that were already present in the unfertilized egg
• D. present in larger quantities than is necessary for the development of a single individual

Answer 1

The correct option is D present in larger quantities than is necessary for the development of a single individual

D is the best answer. The second and third paragraphs of the passage indicate that morphogenetic determinants are substances in the embryo that are activated after the egg has been fertilized and that “tell a cell what to become” (lines 21-23). If, as the author asserts in the first paragraph, biologists have succeeded in dividing an embryo into two parts, each of which survives and develops into a normal embryo, it can be concluded that the quantity of morphogenetic determinants in the early embryo is greater than that required for the development of a single individual.