Which term describes a membrane that allows some substances to pass through but not all?

Which term describes a membrane that allows some substances to pass through but not all?

• A. Permeability
• B. Selective permeability
• C. Semipermeable
• D. Diffusion

Answer: (B)

Selective permeability is the property of a membrane that allows some substances to pass through while keeping others out. This selectivity comes from the membrane’s structure and transport proteins that create specific pathways for certain molecules based on size, charge, and polarity. Small nonpolar molecules can diffuse through the lipid bilayer, while ions or large polar molecules need channels or carriers. Semipermeable is a closely related way of describing the same idea, but selective permeability highlights the discrimination between different substances. Permeability alone is a general term for how easily something crosses a membrane, and diffusion is the process of movement down a concentration gradient that can occur through a selective membrane, not the descriptor of the membrane itself.

Selective permeability is the property of a membrane that allows some substances to pass through while keeping others out. This selectivity comes from the membrane’s structure and transport proteins that create specific pathways for certain molecules based on size, charge, and polarity. Small nonpolar molecules can diffuse through the lipid bilayer, while ions or large polar molecules need channels or carriers. Semipermeable is a closely related way of describing the same idea, but selective permeability highlights the discrimination between different substances. Permeability alone is a general term for how easily something crosses a membrane, and diffusion is the process of movement down a concentration gradient that can occur through a selective membrane, not the descriptor of the membrane itself.