41. Channel proteins facilitate the transport of molecules by active transport (

Question

41. Channel proteins facilitate the transport of molecules by active transport (a) True 42. Channels allow the appropriate ions or small molecules to pass through. (b) False (b) False (c) Light-driven pump (a) True 43. All of the following are transmembrane pumps that facilitate active transport except? (a) ATP-driven pumps (b) Channel pumps 44. Neurotransmitters are secreted into a specialized junction known as the (d) Coupled pumps (a) Synapse (c) Ligand channel (b) Synaptic vesicles (d) Axon 45. How does nerve impulses travel from one neuron to another? (a) Chemical > Chemical Electrical (b) Electrical ChemicalChemical (c) Chemical Electrical Chemical (d) Electrical Chemical Electrical 46. Neuron is stimulated, the membrane potential of the plasma membrane shifts to a less negative value by opening voltage-gated K' channels: (a) True (b) False 47. Once a neuron is stimulated and the membrane potential is depolarized, the depolarized axonal membrane is helped to return to its resting potential by opening voltage-gated K+ channels, allowing K+ to flow out of the cell down its concentration gradient (a) True (b) False 48. Spectrin is a protein found in the plasma membrane of all eukaryotic cells that provide support to the plasma membrane. (a) True (b) False 49. Transmembrane proteins allow large particles to pass through the membrane. (a) True (b) False 50. Prokaryotes adapt to hot temperatures by increasing the length of their hydrophobic tails and decreasing the amount of double bonds in their phospholipid bilayer (a) True (b) False

Explanation / Answer

Que 41.

Ans:

Channel proteins facilitate the transport of molecules by active transport: False.

Explanation:

- Channel proteins facilitate the transport of molecules by passive transport.

- Passive transport occurs along the concentration gradient and without use of metabolic energy.

- Passive transport include simple diffusion and facilitated diffusion.

- Two classes of proteins that mediate facilitate diffusion are generally distinguished: Carrier proteins and Channel proteins.

- Channel proteins form open pores through the membrane, allowing free diffusion of any molecules of the appropriate size and charge.

Que 42.

Ans:

Channels allow the appropriate ions or small molecules to pass through: True.

Explanation:

- Channel proteins form open pores through the membrane, allowing the free diffusion of any molecules of the appropriate size and charge.

- Rate of diffusion mediated by channel proteins is higher than those mediated by carriers.

- One group of channel proteins, is the porins, which permit the free passage of ions and small polar molecules through the outer membrane of bacteria.

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