Question

which of the following structures serves as the cell’s boundary from its environment?
○ mitochondrion
○ cell membrane
○ chloroplast
○ channel proteins

Explanation:

• Mitochondrion: Functions in energy production (cellular respiration), not as a cell boundary.
• Cell membrane: Also called plasma membrane, it regulates what enters and exits the cell, acting as the cell's boundary from the environment.
• Chloroplast: Involved in photosynthesis in plant cells, not a boundary structure.
• Channel proteins: Are part of the cell membrane and help in transport, but the cell membrane as a whole is the boundary.

Answer:

B. cell membrane