Question

Why do cattle avoid browsing on the plant Calotropis?

• A. It bears thorns
• B. Both a and b
• C. It produces highly poisonous compound opium
• D. It produces poisonous cardiac glycosides

Answer 1

The correct option is D It produces poisonous cardiac glycosides

Predation is a type of interspecific interaction in which the predator eats another organism called prey. The predator is represented by ‘+’ sign as it gets benefited and ‘-’ sign is used to indicate prey as it gets harmed.

If over-exploited by predators, the prey species will go extinct. Therefore, the prey species have developed certain defence mechanisms to reduce the impact of predation.

The predators of plants are herbivores. Unlike animals, plants cannot run away from their predators. Hence, plants have developed a remarkable variety of morphological and chemical defences against herbivores.

Some of them include:

• Thorns: These are hard, woody pointed structures that offer protection to plants and prevent the grazing animals from eating the plants. Examples of plants producing thorns are Acacia and Bougainvillea.
• Calotropis commonly called milkweed produces very toxic chemicals called cardiac glycosides that affect the heart. Hence, cattle avoid browsing on this plant.
• Opium is obtained naturally from the poppy plant, opium poppy. It contains several alkaloids like morphine, codeine etc. These chemicals are produced by plants as defences against the grazers and browsers.

Hence, option b is correct.