Question

Mention how have plants developed mechanical and chemical defence against herbivores to protect themselves with the help of one example of each.

Answer 1

Plants have developed the mechanical and chemical defence as:

1. Mechanical defence: Plants protect themselves by developing modified structures such as thorns, which act as defensive organs. Examples include Acacia and Cactus.
2. Chemical defence: Plants defend themselves by producing and storing toxic chemicals like cardiac glycosides, nicotine, caffeine, quinine, strychnine, and opium. For example, Calotropis contains cardiac glycosides that help protect the plant from grazing animals.