Questions: All cells are surrounded by cell membranes, also called plasma membranes, that separate the cytoplasm from the outside environment. ribosomes. Golgi apparatus. endoplasmic reticulum Need help? Review these concept resources.

The answer is the first one: the outside environment.

Explanation for each option:

1. The outside environment: This is the correct answer. The primary function of the cell membrane (or plasma membrane) is to separate the internal contents of the cell, including the cytoplasm, from the external environment. This barrier regulates the movement of substances in and out of the cell, maintaining homeostasis.

2. Ribosomes: This is incorrect. Ribosomes are cellular structures responsible for protein synthesis. They can be found floating freely in the cytoplasm or attached to the endoplasmic reticulum, but they are not separated from the cytoplasm by the cell membrane.

3. Golgi apparatus: This is incorrect. The Golgi apparatus is an organelle involved in modifying, sorting, and packaging proteins and lipids for secretion or delivery to other organelles. It is located within the cytoplasm and is not separated from it by the cell membrane.

4. Endoplasmic reticulum: This is incorrect. The endoplasmic reticulum (ER) is a network of membranous tubules within the cytoplasm of the cell. It plays a role in the synthesis of proteins and lipids. Like the Golgi apparatus, it is part of the internal cellular structure and is not separated from the cytoplasm by the cell membrane.

Summary: The cell membrane, or plasma membrane, separates the cytoplasm from the outside environment, ensuring the cell's internal environment is maintained and regulated.