What is does the cell membrane do for the cell?
A. Hold DNA
B. Allows molecules in and out of cell
C. Makes proteins
D. Holds organelles in place
B. Allows molecules in and out of cell
B. Allows molecules in and out of cell
The correct answer is B. The cell membrane allows molecules in and out of the cell. To arrive at this answer, we can eliminate options A, C, and D because they are not the primary function of the cell membrane. Option A, holding DNA, is incorrect because the DNA is housed within the nucleus of the cell, not the cell membrane. Option C, making proteins, is incorrect because protein synthesis occurs within the ribosomes and endoplasmic reticulum, not the cell membrane. Option D, holding organelles in place, is incorrect because the organelles, such as the nucleus, mitochondria, and endoplasmic reticulum, have their own membranes and structures that hold them in place.
The primary function of the cell membrane is to regulate the movement of substances in and out of the cell. It is selectively permeable, meaning it allows some substances to pass through while restricting the movement of others. Small molecules can passively diffuse across the cell membrane, but larger or charged molecules require the assistance of specialized transport proteins. This selective permeability helps maintain the internal environment of the cell and allows it to interact with its surrounding environment.