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7 a. The structure labelled A is the nucleus.
b. The organelle labelled B is the nuclear membrane.
c. The small dark round objects labelled C are ribosomes.
d. The long tubes labelled D are rough endoplasmic reticulum.
e. The name of the structure labelled P is a nuclear pore (hole
in the surface of the nuclear envelope).
f. The name of the organelle labelled M is mitochondria.
Long & Slichter