Which of the following statement about facilitated diffusion is true?
1) facilitated diffusion is the same as diffusion, except for the fact that membrane proteins are involved in transporting molecules or ions
2) the ions from the region of higher concentration on one side of a membrane is transported to the region of lower concentration on the other side of the membrane
3) glucose molecule, a vital energy source for our body, is absorbed into our cells through protein channels during facilitated diffusion
4) statements i, ii, and iii
The Correct Answer and Explanation is:
The correct answer is 1) Facilitated diffusion is the same as diffusion, except for the fact that membrane proteins are involved in transporting molecules or ions.
Here’s an explanation of why this statement is correct, and the others are not:
Facilitated Diffusion:
Facilitated diffusion is a type of passive transport, which means it does not require energy (ATP). In both simple diffusion and facilitated diffusion, molecules move from an area of higher concentration to an area of lower concentration, following their concentration gradient. However, the key difference between the two lies in the role of membrane proteins.
- Facilitated diffusion involves specific proteins (such as carrier proteins or channel proteins) in the cell membrane to help molecules that are not able to pass directly through the lipid bilayer (due to size, charge, or polarity). These membrane proteins provide a pathway that facilitates the transport of these molecules, such as glucose, ions, or other large or charged molecules.
In contrast, simple diffusion does not require membrane proteins. Molecules move directly through the lipid bilayer, typically small and nonpolar molecules like oxygen or carbon dioxide.
Analysis of the other statements:
2) The ions from the region of higher concentration on one side of a membrane are transported to the region of lower concentration on the other side of the membrane.
- While this is true, it is a description of diffusion in general and does not specifically refer to facilitated diffusion. Facilitated diffusion works in this manner but requires proteins, which the statement does not mention.
3) Glucose molecule, a vital energy source for our body, is absorbed into our cells through protein channels during facilitated diffusion.
- This is incorrect because glucose is typically transported via carrier proteins, not protein channels. While both are forms of facilitated diffusion, glucose specifically uses carrier proteins (such as GLUT transporters), which change shape to move glucose across the membrane. Protein channels are usually involved in transporting ions or small molecules.
4) Statements i, ii, and iii provide the correct answer.
- Since statement 3 is inaccurate, statement 4 cannot be correct.
Conclusion:
Statement 1 correctly describes facilitated diffusion by acknowledging the role of membrane proteins in the transport of molecules, making it the best answer. Facilitated diffusion is a crucial process for the movement of larger or polar molecules across cell membranes, enabling cells to intake essential substances like glucose.