Identify the type of transport (passive diffusion, facilitated transport, or active transport) that will occur for the following molecules:
(b) glucose, no energy required

Verified step by step guidance

1. Understand the three types of transport mechanisms: Passive diffusion involves movement of molecules from high to low concentration without energy or assistance. Facilitated transport also moves molecules from high to low concentration but requires a protein channel or carrier. Active transport moves molecules against the concentration gradient (low to high) and requires energy (ATP).
2. Analyze the molecule in question, glucose. Glucose is a polar molecule and relatively large, which means it cannot pass directly through the hydrophobic lipid bilayer of the cell membrane by passive diffusion.
3. Determine if energy is required for the transport. The problem specifies 'no energy required,' which rules out active transport.
4. Consider facilitated transport. Glucose often uses protein carriers or channels to move across the membrane without requiring energy, making facilitated transport the likely mechanism.
5. Conclude that the transport mechanism for glucose, given that no energy is required, is facilitated transport, as it relies on protein channels or carriers to move across the membrane.

Key Concepts

Passive Diffusion

Passive diffusion is the movement of molecules across a cell membrane without the need for energy input. This process occurs when molecules move from an area of higher concentration to an area of lower concentration, following their concentration gradient. Small, nonpolar molecules, such as oxygen and carbon dioxide, typically utilize this method to enter or exit cells.

Facilitated Transport

Facilitated transport, also known as facilitated diffusion, is a type of passive transport that requires specific transport proteins to help move molecules across the cell membrane. This process is essential for larger or polar molecules, like glucose, which cannot easily pass through the lipid bilayer. Facilitated transport does not require energy, as it still relies on the concentration gradient.

Active Transport

Active transport is the movement of molecules across a cell membrane against their concentration gradient, which requires energy, usually in the form of ATP. This process is crucial for maintaining cellular concentrations of ions and nutrients, allowing cells to uptake substances even when they are in lower concentrations outside. Examples include the sodium-potassium pump and proton pumps.