In the classic experiments by Bracht and Hammerling, the nucleus of Acetabularia was removed, the cap was cut off, a nucleus of a different species was inserted, and the cap was allowed to regenerate.The new cap was then removed.After the second regeneration, the cap was observed, and the following conclusion was made:
A) The shape of the cap was controlled by the nucleus, thus, the nucleus was the control center of the cell.
B) The shape of the cap was under the control of the stalk, which produced a control substance.
C) The shape of the cap was independent of both the stalk and the holdfast.
D) The "cren" caps were defective due to some mutation in the cap.Thus, "cren" caps are independent of control from both the base and the holdfast.
E) At the time no conclusion could be made because in the early 20th century, biologists did not know about the composition of DNA.

Question

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The experiments demonstrated that the nucleus controlled the shape of the cap, indicating that the nucleus acts as the control center of the cell.

In the Classic Experiments by Bracht and Hammerling, the Nucleus