Calotropis, a weed commonly found in abandoned fields, produces which of the following biochemicals as a defence mechanism against grazers and browsers?
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → Cardiac glycosides
For plants, herbivores are the predators. Plants cannot run away, so many of them defend themselves with chemicals that make the herbivore sick or even kill it. The weed Calotropis produces highly poisonous cardiac glycosides. Caffeine, quinine and strychnine are also plant chemicals that defend against grazers and browsers, but they come from other plants.
NCERT Extract:
Population Interactions – “… Many plants produce and store chemicals that make the herbivore sick when they are eaten, inhibit feeding or digestion, disrupt its reproduction or even kill it. You must have seen the weed Calotropis growing in abandoned fields. The plant produces highly poisonous cardiac glycosides and that is why you never see any cattle or goats browsing on this plant. A wide variety of chemical substances that we extract from plants on a commercial scale (nicotine, caffeine, quinine, strychnine, opium, etc.,) are produced by them actually as defences against grazers and browsers.”