Q.39. Discuss one example, based on your day-to-day observation, showing how the loss of one species may lead to the extinction of another.

Co-extinction is the extinction of two mutually related or interrelated species for instance a host fish extinction leads to the extinction of all those parasites exclusively found on it. Another example is plant-pollinator mutualism, where the extinction of one leads to the extinction of another.
Insect, aphids are polyphagous (feed on more than one plant species) or monophagous (feed on a particular species of plant). Monophagous insects may become extinct if the plant species upon which they feed becomes extinct.