Exploring Passive and Active Transport Mechanisms

Cells exchange materials with their environment through passive and active transport. Passive transport involves the diffusion of small molecules like oxygen and water across a semi-permeable membrane without energy. Facilitated transport, a type of passive transport, uses carrier proteins to move larger molecules like glucose. Active transport requires energy to move ions like sodium and potassium against their concentration gradients, using mechanisms such as the sodium-potassium pump.

What is the primary difference between passive and active transport?

• Neither requires energy.

• Passive transport requires energy, while active transport does not.

• Active transport requires energy, while passive transport does not.

• Both require energy.

Which of the following molecules can freely diffuse across the cell membrane?

• Starches

• Oxygen

• Glucose

• Proteins

What prevents ions from simply diffusing across the cell membrane?

• The presence of carrier proteins

• Their electrical charge

• Their size

• The concentration gradient

How do large molecules like glucose move across the cell membrane?

• Via carrier proteins

• Through ion channels

• By dissolving in the lipid bilayer

• Through simple diffusion

What is the role of carrier proteins in facilitated transport?

• They break down molecules for transport.

• They provide energy for the transport process.

• They change shape to move molecules across the membrane.

• They create a concentration gradient.

What is the function of the sodium-potassium pump?

• To transport oxygen and carbon dioxide.

• To facilitate the diffusion of glucose.

• To move sodium and potassium ions against their concentration gradients.

• To move sodium and potassium ions along their concentration gradients.

What molecule provides energy to the sodium-potassium pump?

• Carbon dioxide

• ATP

• Glucose

• Oxygen

What happens to the sodium-potassium pump after it releases potassium ions inside the cell?

• It binds to more sodium ions.

• It binds to more potassium ions.

• It stops functioning.

• It releases energy.

Why does the sodium-potassium pump require energy?

• To move ions along their concentration gradients.

• To break down ATP.

• To facilitate passive transport.

• To move ions against their concentration gradients.

What is the main characteristic of active transport?

• It does not require energy.

• It requires energy to move molecules against their concentration gradient.

• It moves molecules along their concentration gradient.

• It only occurs in plant cells.