IMMUNOLOGY

Detailed explanation-1: -When coffee leaves die and fall to the ground, they contaminate the soil with caffeine, which makes it difficult for other plants to germinate. Coffee may thus use caffeine to kill off the competition. Coffee plants also use caffeine to ward off insects that would otherwise feast on their leaves and beans.

Detailed explanation-2: -Studies have shown that caffeine is a natural pesticide. It gives off a bitter odour to ward off or kill insects that come to feed on it. While caffeine is generally safe for humans, it can be toxic to pets and should be kept away from cats, dogs, and birds.