* Structure IS essential for transport: Cells have specialized structures that control what enters and leaves. These include:

* Cell membrane: The outer layer of the cell acts as a selective barrier, allowing some substances to pass through while blocking others.

* Proteins embedded in the membrane: These proteins act as channels, pumps, and receptors, facilitating the movement of specific molecules.

* Organelles: Structures like the endoplasmic reticulum and Golgi apparatus are involved in packaging and transporting molecules within the cell.

* Structure alone is NOT enough: Transport is also governed by several factors:

* Concentration gradients: Molecules move from areas of high concentration to low concentration (passive transport).

* Active transport: Requires energy to move molecules against their concentration gradient.

* Chemical properties of the molecules: Size, charge, and solubility influence whether a molecule can cross the membrane.

Therefore, structure provides the framework for transport, but the actual movement of molecules is driven by a combination of structural features and other factors.