Cell transport: Diffusion and facilitated diffusion

Which of the following is true for simple diffusion across the plasma membrane?

• It requires ATP energy.

• It occurs along a concentration gradient.

• It involves the use of transport proteins.

• It only occurs in the presence of water.

Which of the following is a characteristic feature of facilitated diffusion?

• It occurs against the concentration gradient.

• It requires ATP energy to move molecules.

• It involves specific membrane proteins such as carriers or channels.

• It is restricted to small, non-polar molecules.

Which of the following molecules would be most likely to diffuse across the plasma membrane by simple diffusion?

• Glucose

• Sodium ions (Na⁺)

• Oxygen (O₂)

• Amino acids

What is the primary role of channel proteins in facilitated diffusion?

• To hydrolyze ATP for energy.

• To form pores that allow specific ions or molecules to pass through the membrane.

• To increase the rate of active transport.

• To bind to molecules and carry them across the membrane.

Which of the following statements about facilitated diffusion is FALSE?

• It occurs with the concentration gradient.

• It requires transport proteins but not ATP.

• It moves molecules from areas of low to high concentration.

• It can transport both small and large molecules, depending on the protein.

What factor would most likely increase the rate of diffusion across the plasma membrane?

• A decrease in the surface area of the membrane.

• A decrease in the temperature of the environment.

• An increase in the concentration gradient of the substance.

• An increase in the size of the molecules being transported.

Which of the following is a factor that can affect the rate of facilitated diffusion?

 

• The size of the transport protein.

• The presence of ATP.

• The presence of water molecules.

• The thickness of the plasma membrane.

What happens when a channel protein becomes saturated during facilitated diffusion?

• The rate of diffusion increases further.

• The molecules are transported faster than normal.

• The rate of diffusion reaches a maximum and cannot increase.

• The molecules will begin to move against the concentration gradient.

Which of the following substances is most likely to be transported by facilitated diffusion?

• Glucose

• Water

• Oxygen

• Carbon dioxide

Which of the following statements about the plasma membrane is true regarding diffusion?

• The plasma membrane allows all molecules to diffuse across at the same rate.

• Both diffusion and facilitated diffusion require energy in the form of ATP.

• Simple diffusion occurs through transport proteins in the membrane.

• The plasma membrane is selectively permeable, allowing only non-polar molecules to diffuse freely.