What term describes the property of a membrane that allows some substances to enter while keeping others out?

What term describes the property of a membrane that allows some substances to enter while keeping others out?

• A. Selective Permeability
• B. Passive Transport
• C. Facilitated Diffusion
• D. Osmosis

Answer: (A)

The property of a membrane that allows some substances to enter while keeping others out is called selective permeability. This characteristic is crucial for maintaining the internal environment of cells, allowing essential nutrients and ions to enter while preventing harmful substances from crossing the membrane. Selective permeability is primarily due to the structure of the phospholipid bilayer that makes up the cell membrane, along with embedded proteins that contribute to the regulation of what can pass through. Small, non-polar molecules can often diffuse freely, while ions and larger polar molecules require specific transport mechanisms. In contrast, passive transport refers to the movement of substances across the membrane without the use of energy, but it does not specifically address the selective aspect. Facilitated diffusion is a type of passive transport that involves specific proteins assisting in the movement of certain molecules, but it is still part of the broader concept of selective permeability. Osmosis specifically refers to the movement of water across a selectively permeable membrane and does not encompass the broader range of substances. Therefore, selective permeability accurately describes the membrane’s ability to differentiate between various substances, ensuring that the cell can maintain homeostasis and function effectively.

The property of a membrane that allows some substances to enter while keeping others out is called selective permeability. This characteristic is crucial for maintaining the internal environment of cells, allowing essential nutrients and ions to enter while preventing harmful substances from crossing the membrane.

Selective permeability is primarily due to the structure of the phospholipid bilayer that makes up the cell membrane, along with embedded proteins that contribute to the regulation of what can pass through. Small, non-polar molecules can often diffuse freely, while ions and larger polar molecules require specific transport mechanisms.

In contrast, passive transport refers to the movement of substances across the membrane without the use of energy, but it does not specifically address the selective aspect. Facilitated diffusion is a type of passive transport that involves specific proteins assisting in the movement of certain molecules, but it is still part of the broader concept of selective permeability. Osmosis specifically refers to the movement of water across a selectively permeable membrane and does not encompass the broader range of substances.

Therefore, selective permeability accurately describes the membrane’s ability to differentiate between various substances, ensuring that the cell can maintain homeostasis and function effectively.