What will be the immediate effect on population when primary consumers number decline?
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → Decrease in secondary consumers
In a food chain each level feeds on the level below it: producers, then primary consumers (herbivores), then secondary consumers (carnivores that eat herbivores). So every level depends on the one below it for its food.
(1) Decrease in secondary consumers — Correct. When the primary consumers decline, the secondary consumers lose their food. Many of them starve or move away, so their number falls. This is the first effect on the population.
(2) Increase in secondary consumers — Incorrect. Less food cannot support more consumers.
(3) Decline in producers — Incorrect. Fewer herbivores eat the plants, so the producers do not decline. They tend to increase.
(4) No change in food chain — Incorrect. The levels are linked by feeding. A change at one level always passes to the next level.