Arrange the following food chains in a proper sequence.
Frog, Snail, Crow, Green leaves
Topic: Food chains — terrestrial
Answer
GREEN LEAVES → SNAIL → FROG → CROW
The same method. GREEN LEAVES are the producer, so they come first. Then: snail eats the leaves (herbivore, primary consumer) frog eats the snail (secondary consumer) crow eats the frog (tertiary consumer)
Note that the terms PRODUCER and CONSUMER matter more than the organisms. Whatever animals a question gives you, the producer is always the green plant, and the chain builds upward from it.
A useful check: energy is lost at every step (only about 10% passes on), which is why food chains rarely have more than four or five links. If your answer has the big animal eating the plant and the small one at the top, it is the wrong way round.