It can be inferred from the passage that the morphogenetic determinants present

游客2024-01-13  28

问题 It can be inferred from the passage that the morphogenetic determinants present in the early embryo are______ [br] It can be inferred from the passage that the initial production of histones after an egg is fertilized takes place______

选项 A、in the cytoplasm
B、in the maternal genes
C、throughout the protoplasm
D、in the beaded portions of the DNA strings
E、in certain sections of the cell nucleus

答案 A

解析 A is the best answer. In the third paragraph, the author asserts that substances that function as morphogenetic determinants are located in the cytoplasm of the cell and become active after the cell is fertilized. In the fourth paragraph we learn that these substances are “maternal messenger RNA’s” and that they “direct, in large part, the synthesis of histones,” which, after being synthesized, “move into the cell nucleus” (lines 59-68). Thus, it can be inferred that after the egg is fertilized, the initial production of histones occurs in the cytoplasm.
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