The original pair "Cells : Cytology" indicates a relationship where "Cytology" is the study of "Cells."
We need to find the pair that exhibits a similar relationship.
Looking at the options:
- Option (1) "Worms : Ornithology" is incorrect because "Ornithology" is the study of birds, not worms.
- Option (2) "Insects : Entomology" is correct because "Entomology" is the study of insects, just as "Cytology" is the study of cells.
- Option (3) "Diseases : Physiology" is incorrect because "Physiology" is the study of bodily functions, not directly related to diseases in this context.
- Option (4) "Tissues : Morphology" is incorrect because "Morphology" refers to the study of structure, which doesn't fit the "study of" relationship.
Thus, the correct relationship is:
\[
\text{Insects} \quad : \quad \text{Entomology}
\]