Exploring Facilitated Diffusion in Cell Membranes

Facilitated diffusion is a passive transport process that helps polar or charged molecules cross the cell membrane using specific transport proteins. Unlike simple diffusion, it requires channel and carrier proteins to assist molecules that cannot easily pass through the lipid bilayer. Channel proteins form pores for specific ions or molecules, while carrier proteins undergo conformational changes to transport molecules across the membrane. This process is highly specific and does not require energy, relying on concentration gradients. The rate of diffusion is limited by the number of available transport proteins, leading to saturation. Examples include glucose transporters and ion channels. Facilitated diffusion is crucial for maintaining cellular homeostasis.

What type of transport process is facilitated diffusion?

• Endocytosis

• Exocytosis

• Passive transport

• Active transport

Which of the following is NOT a characteristic of facilitated diffusion?

• Requires transport proteins

• Moves molecules against their concentration gradient

• Does not require cellular energy

• Transports polar or charged molecules

What do channel proteins form in the cell membrane?

• Channels or pores

• Enzymes

• Receptors

• Vesicles

Which of the following is an example of a channel protein?

• ATP synthase

• Hemoglobin

• Aquaporin

• Glucose transporter

How do carrier proteins transport molecules across the membrane?

• By using ATP

• By forming pores

• By binding and undergoing a conformational change

• By engulfing the molecules

What induces a carrier protein to change its shape?

• pH change

• Temperature change

• Binding of the molecule

• Presence of ATP

What ensures that only necessary molecules are transported in facilitated diffusion?

• The temperature of the environment

• The specificity of transport proteins

• The size of the cell

• The pH level

What happens when all transport proteins are in use during facilitated diffusion?

• The transport proteins are destroyed

• The rate of diffusion increases

• The rate of diffusion plateaus

• The cell stops functioning

Which molecule uses glucose transporters for facilitated diffusion?

• Sodium

• Glucose

• Calcium

• Potassium

What is the role of aquaporins in facilitated diffusion?

• Synthesizing proteins

• Binding glucose

• Facilitating the diffusion of water molecules

• Transporting ions