Cattle or goats are not seen browsing on Calotropis due to:

The correct answer is Option (4) → Cardiac glycosides

Plants cannot run away from animals that eat them, so many plants defend themselves with chemicals. Calotropis is a common weed of abandoned fields. It makes highly poisonous cardiac glycosides, which act on the heart. So cattle and goats do not graze on it. This is a chemical defence against herbivores.

(1) Cardiac glycoproteins — Incorrect. Glycoproteins are proteins with sugar chains attached. There is no such plant poison as a “cardiac glycoprotein”; the word has been made from “glycoside”.

(2) Cardiac lipids — Incorrect. No such group of poisons exists. Lipids are fats and oils.

(3) Cardiac nucleosides — Incorrect. No such group of poisons exists. Nucleosides are a base joined to a sugar, the building blocks of nucleic acids.

(4) Cardiac glycosides — Correct. These are the poisonous chemicals of Calotropis.

Note: A similar question was also asked in CUET (UG) 2026 on 31-05-2026 (Slot 2).

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.”