MCQs

The phosphate group is ionized and hydrophilic, ensuring the "head" interacts with the aqueous environment.

Simple diffusion occurs directly through the lipid bilayer for small, non-polar molecules.

Lipids can self-seal due to the hydrophobic effect, reforming the bilayer automatically.

Cholesterol intercalates between the fatty acid tails, stabilizing the membrane.

Plasmalemma is a biological synonym for the plasma membrane.

High heat increases the kinetic energy of lipid tails, increasing the membrane's fluidity.

The Na+/K+ pump moves ions against their gradients using ATP, defining it as active transport.

Amphipathic molecules are essential for forming the bilayer as they interact with both aqueous and non-aqueous environments.

Transmembrane pumps (like the Na+/K+ pump) use ATP to change conformation and transport ions.

Transmembrane proteins are a subset of integral proteins that traverse both leaflets of the bilayer.

Glycoproteins and glycolipids act as cellular "identity tags" and mediate cell-cell adhesion.

Cell wall thickness is unrelated to the fluidity of the plasma membrane.

Carbohydrate chains are attached to proteins/lipids only on the non-cytosolic side of the membrane.

Passive transport relies on kinetic energy (gradient), while active transport requires metabolic energy (ATP).

Facilitated diffusion requires either channel or carrier proteins to assist polar molecules.

The two hydrocarbon chains (fatty acids) are non-polar and hydrophobic.

The phospholipid bilayer provides the fundamental hydrophobic barrier essential for cellular compartmentalization.

By measuring the surface area of extracted lipids, they determined it was twice the surface area of the RBC.

The membrane is fluid and dynamic, not rigid or crystalline.