Facilitated Diffusion

Q. The porins are proteins that form large pores, allowing molecules up to the size of small proteins to pass through. They are found in:

1. Membranes of some bacteria
2. Membrane of ribosomes
3. Outer membranes of the mitochondria
4. Outer membranes of the plastids

Q.

Transport against the concentration gradient can be done without using energy.

1. True

2. False

Q. Rate of diffusion across cell membrane depends upon

1. Solubility in lipids

2. Size of the substances

3. Both a & b

4. Living system

Q.

What characteristic is shared by simple diffusion and facilitated diffusion?

1. Both require cellular energy for the transport of substances.

2. Both involve the movement of water across a semipermeable membrane.

3. Both require a special carrier molecule to move substances across the membrane.

4. Both involve the movement of a substance from regions of a higher concentration to lower concentration without cellular energy

Q. Porins are the proteins that form huge pores in the membranes

1. True

2. False

Q. Diffusion that occurs through carrier proteins is

1. Simple diffusion

2. Passive diffusion

3. Facilitated diffusion

4. Active diffusion

Q. Hydrophilic moieties cannot diffuse across the plasma membrane.

1. False

2. True

Q.

Identify P, Q & R in the figure

1. P - Uniport, Q - Symport, R - Antiport

2. P - Uniport, Q - Antiport, R - Symport

3. P - Antiport, Q - Symport, R - Uniport

4. P - Symport, Q - antiport, R - Uniport

Q. Identify the incorrect statement related to facilitated diffusion.

1. Substances are transported without the use of ATP.
2. Causes net transport of molecules from low to high concentration
3. Transport rate reaches saturation.
4. Very specific and selective to substances

Q. Select the correct statements about facilitated diffusion.

1. There is a specific protein carrier for a specific substance to be transported.
2. The same protein carrier transports all the substance through the membrane.
3. There is no limit to the rate of transport of a substance by facilitated diffusion.
4. The rate of transport is limited by saturation, i.e. when all protein carrier molecules are being used.