biolgist concludes that a molecule moves across cell membrane by facilitated diffusion because the molecule is small, polar and can accumulate inside cells even when its concentration inside the cell initially is higher that it is outside the cell and they use up more energy when the molecule is present in the environment around the cells than when it is not present. Agree or disagree? why or why not? confused....thanks for your help
Based on the information provided, it seems clear that the biologist has concluded that the molecule moves across the cell membrane by facilitated diffusion. Let's break down the given reasons to agree or disagree with this conclusion:
1. The molecule is small and polar: Facilitated diffusion involves the movement of molecules across a membrane with the help of proteins. Small, polar molecules, like ions or certain types of sugars, generally require the assistance of transport proteins to pass through the hydrophobic core of the cell membrane. Hence, the fact that the molecule is small and polar supports the conclusion of facilitated diffusion.
2. The molecule can accumulate inside cells even when its initial concentration inside the cell is higher than outside: In facilitated diffusion, the movement of molecules is driven by their concentration gradient. That means if the molecule can accumulate inside the cell even when there is a higher initial concentration inside, it suggests that a transport protein is involved. The presence of such proteins would allow the molecule to move against its concentration gradient, which is characteristic of facilitated diffusion.
3. More energy is used up when the molecule is present in the environment around the cells: This statement is a bit confusing. Typically, facilitated diffusion does not require the input of energy. In fact, it relies on the energy stored in the concentration gradient of the molecule to move it across the membrane. If this statement is accurate, it suggests that some type of active transport mechanism may be involved, rather than facilitated diffusion. Active transport requires the input of cellular energy, such as ATP, to move molecules against their concentration gradient.
In summary, based on the given information, it is reasonable to agree with the biologist's conclusion that the molecule moves across the cell membrane by facilitated diffusion due to its small size, polarity, and the ability to accumulate inside the cell even with a higher initial concentration. However, the statement about increased energy usage is contradictory to the concept of facilitated diffusion, so it may be useful to clarify that point with the biologist.