Question

multiple choice question
the endoplasmic reticulum is a membranous network extending from the ______ throughout the cytoplasm.

○ plasma membrane
○ nuclear envelope
○ nucleolus

Explanation:

To solve this, we recall the structure of the endoplasmic reticulum (ER). The ER is a membranous network that starts from the nuclear envelope and extends into the cytoplasm. The plasma membrane is the cell's outer membrane, not the origin of ER. The nucleolus is inside the nucleus and not related to the ER's origin. So the correct option is the nuclear envelope.

Answer:

B. nuclear envelope (assuming the options are labeled as A. plasma membrane, B. nuclear envelope, C. nucleolus)