Which factor is crucial for maintaining the integrity of a biological sample during preservation?

Maintaining the integrity of a biological sample during preservation is fundamentally linked to temperature control. Proper temperature regulation is essential because biochemical processes, including enzymatic reactions and microbial growth, can proceed at varying rates depending on the temperature.

When a biological sample is kept at an appropriate temperature, it minimizes the risk of degradation, contamination, and loss of cellular function. For instance, low temperatures can slow down or halt these processes, preserving the sample's original state for longer periods. This is particularly significant in cases where samples are being stored for future analysis, research, or diagnostic purposes.

The other options presented do not contribute positively to the preservation of biological samples. Increasing sample size may introduce more variability and potential degradation points, utilizing non-biological materials may lead to contamination or interference with the sample’s natural state, and applying excessive heat can denature proteins and alter biological processes, ultimately compromising the sample's integrity. Thus, temperature control stands out as the most crucial factor in this context.