Protozoan cysts — identify the choice that is NOT a function of cyst formation (note: encystment protects, aids transmission, and may involve nuclear reorganization).

Introduction:
Protozoan cysts are dormant, resistant forms that help organisms survive unfavorable conditions and, in parasitic species, facilitate transmission. The question asks which option is not a function, inviting us to evaluate each role attributed to cysts.

Given Data / Assumptions:

• Cysts may provide protection.
• Cysts can participate in nuclear reorganization or division in some taxa.
• Cysts often serve as transmissive stages between hosts (e.g., fecal-oral spread).

Concept / Approach:
We compare each proposed function against established protozoology. Encystment enhances environmental resistance (desiccation, chemicals, temperature). In several species, nuclear events occur during encystment/excystment. Parasitic protozoa commonly use cysts to move from one host to another.

Step-by-Step Solution:

Verification / Alternative check:
Textbook life cycles of intestinal protozoa highlight cysts as the infective, durable form. Laboratory observations document nuclear events during encystment in several genera.

Why Other Options Are Wrong:

• Protection: core purpose of cysts.
• Nuclear events: occur in specific species.
• Transmission: key epidemiological role.

Common Pitfalls:
Assuming cysts only protect but never undergo nuclear changes; ignoring parasitic transmission stages.

Final Answer:
None of the above (all listed are valid functions of cysts)