A Level Biology Practice Exam 2025 – All-in-One Study Guide to Excel in Your A Levels!

The term that describes a situation where a change is not evenly distributed across a particle is "polar." This term usually refers to situations in chemistry and biology where there is an uneven distribution of charge within a molecule or particle, leading to regions of partial positive and partial negative charges. Polar molecules, such as water, have a distinct dipole moment due to this uneven charge distribution, which significantly influences their interactions and properties, such as solubility and reactivity.

In contrast, the other terms suggest a more uniform state. "Uniform" implies that something is the same throughout. "Isotropic" refers to properties that are identical in all directions, which contradicts the concept of uneven distribution. "Symmetrical" conveys balance and equality, suggesting that any features or changes are evenly mirrored rather than unevenly spread. Therefore, "polar" aptly captures the concept of unevenness in charge or property distribution across a particle.