CELS-4-hard – Churner

Active transport is different from passive transport because it:

Allows substances to pass freely without energy input

Requires ATP to move molecules against their concentration gradient

Occurs only in prokaryotic cells

Moves molecules down their concentration gradient

None

Facilitated diffusion requires ______, which help transport ______ molecules across the membrane, but does not require ______.

Channel proteins; water-soluble; ADP

Ribosomes; charged; cholesterol

Aquaporins; hydrophobic; membrane proteins

Carrier proteins; hydrophilic; ATP

None

The plasma membrane is essential for cellular function because it:

Is selectively permeable, regulating molecular movement while maintaining internal conditions.

is composed of a rigid phospholipid bilayer that maintains a fixed structure.

Forms a completely impermeable barrier, preventing any molecular exchange

Consists entirely of proteins that regulate molecular transport.

None

Which of the following statements about membrane fluidity is false?

Unsaturated fatty acids increase membrane fluidity by preventing tight packing

Phospholipids are static and do not move within the bilayer

Cholesterol helps stabilize membrane fluidity under different temperature conditions

The degree of saturation of fatty acids influences membrane fluidity

None

Which of the following statements is true about passive transport?

It moves molecules down their concentration gradient without using energy

It moves molecules against their concentration gradient

It allows hydrophilic molecules to cross freely without proteins

It requires ATP to function efficiently

None

The plasma membrane consists of a ______ bilayer, where the hydrophilic ______ face outward, and the ______ are oriented inward.

Carbohydrate lipid; heads; phosphate heads

Phospholipid; heads; hydrophobic tails

Phospholipid; tails; fatty acid tails

Protein; fatty acids; cholesterol molecules

None

Which of the following is false regarding membrane transport?

Osmosis requires ATP to move water across the plasma membrane

Passive transport does not require energy and moves molecules down their concentration gradient

Active transport requires ATP to move molecules against their gradient

Facilitated diffusion requires carrier proteins but does not use ATP

None

Co-transport differs from simple diffusion in that:

It only occurs in bacterial cells

It transports molecules down their concentration gradient without assistance

It requires ATP for direct energy expenditure

It uses the gradient of one molecule to drive the movement of another

None

Which of the following is NOT a function of membrane proteins?

Signal transduction

Passive diffusion of small non-polar molecules

Intercellular joining

Cell recognition

None

10.

Which of the following statements about membrane proteins is true?

All membrane proteins are permanently fixed in place within the bilayer and cannot move laterally

Intercellular joining proteins facilitate direct cell-to-cell attachment, while some membrane proteins anchor the cell to the extracellular matrix

Transport proteins only facilitate passive movement of molecules and are never involved in active transport

Glycoproteins are primarily involved in signal transduction rather than cell recognition

None