Discuss one example,based on your day-to-day observations,showing how the loss of one species may lead to the extinction of another.

(N/A) When a species becomes extinct,the plant and animal species associated with it in an obligatory way also become extinct.
For example:
$(i)$ When a fish species that serves as a host for a specific parasite becomes extinct,the parasite species that are uniquely dependent on that host fish will also face extinction.
$(ii)$ Insects can be polyphagous (feeding on more than one plant species) or monophagous (feeding on only one particular plant species).
The monophagous insect species are highly vulnerable and may become extinct if the specific plant species upon which they feed becomes extinct.