CELS-4-revision2

Passive transport moves molecules ______ their gradient, while active transport moves molecules ______, requiring the direct use of ______.

Along; along; energy

Against; against; ATP

Against; along; ATP

Along; against; ATP

None

Membrane proteins play a crucial role in:

Preventing molecular movement across the bilayer entirely

Facilitating transport and signaling transduction

Generating ATP from phospholipid metabolism

Forming a static structure and facilitative transportation

None

The plasma membrane contains amphipathic phospholipids with ______ heads that interact with water and ______ tails that form the hydrophobic interior.

Hydrophilic; non-polar

Hydrophobic; charged

Lipid; protein

Non-polar; polar

None

Which of the following statements about membrane proteins is false?

Glycoproteins play a role in cell-cell recognition, often binding to molecules on neighboring cells

The primary function of intercellular joining proteins is to anchor the cell to the extracellular matrix

Transport proteins can be involved in both passive and active transport mechanisms

Signal transduction proteins relay messages from the extracellular environment into the cell, influencing cellular functions like growth and division

None

Which of the following best explains why small, non-polar molecules can pass through the membrane without assistance?

Their properties allow them to dissolve in the hydrophobic membrane interior

They are small enough to diffuse through membrane channels

They are actively transported using ATP-driven pumps designed for these types of molecules

The hydrophilic lipid tails allow their passage through the bilayer

None

The sodium-potassium pump helps maintain cellular electrochemical gradients by:

Using ATP to move sodium out of the cell and potassium into the cell

Allowing sodium into the cell via passive diffusion

Pumping equal amounts of sodium and potassium ions across the membrane

Transporting both ions down their respective concentration gradients

None

Which of the following is true regarding membrane fluidity?

It decreases when the proportion of unsaturated fatty acids increases

It is maintained by cholesterol

It remains constant regardless of temperature or lipid composition

It depends solely on protein concentration rather than lipid composition

None

The plasma membrane maintains homeostasis by:

Allowing hydrophilic molecules to diffuse freely while restricting hydrophobic molecules

Utilizing membrane proteins exclusively for active transport processes

Preventing all molecules from crossing to preserve internal conditions

Using selective permeability and dynamic protein interactions

None

Which of the following statements is false?

The phospholipid bilayer restricts charged molecules from freely passing

The fluidity of the membrane is influenced by temperature, cholesterol, and fatty acid composition

Membrane proteins facilitate both passive and active transport processes

Cholesterol disrupts membrane integrity, increasing permeability to all molecules

None

10.

The ______ allows eukaryotic cells to maintain compartmentalization, while the ______ regulates the passage of genetic information.

Endoplasmic reticulum; Golgi apparatus

Plasma membrane; nuclear envelope

Mitochondrion; ribosome

Cytoskeleton; plasma membrane

None