Which term refers to the protective sac that microorganisms form in harsh conditions?

The term that refers to the protective sac that microorganisms form in harsh conditions is "cyst." Cysts are specialized structures that some microorganisms, such as protozoa and certain bacteria, produce to survive unfavorable environmental conditions. When faced with stressors like desiccation, extreme temperatures, or nutrient depletion, these microorganisms can initiate the process of encystment, creating a protective barrier around themselves that helps maintain their viability until conditions improve.

This protective sac allows microorganisms to endure prolonged periods of dormancy, becoming resistant to environmental extremes that would otherwise be detrimental to their survival. When conditions become favorable again, the cyst can hatch or break down, allowing the microorganism to revert to its active state and resume growth and reproduction. This unique adaptation is crucial for the survival of many microorganisms in fluctuating environments.

The other terms do not refer to protective structures; for example, pseudopodia are extensions of the cell membrane used for movement and feeding, while a pellicle is a thin layer that provides shape and protection but doesn’t offer the same kind of dormancy strategy. An eyespot is a structure found in some single-celled organisms that aids in light detection, helping them to navigate towards light sources, but it is not involved in protection against