With reference to 'earthworms', which of the following statements is/are correct ?
1. Earthworms improves soil fertility and are known as farmer's friends.
2. Earthworm has two pair of hearts.
Select

Question

With reference to 'earthworms', which of the following statements is/are correct ?
1. Earthworms improves soil fertility and are known as farmer's friends.
2. Earthworm has two pair of hearts.
Select the correct answer from the code given below :

UnlockIAS · Accepted Answer

Correct — D, Only 1. Statement 1 is the settled ecological fact: earthworms swallow soil along with dead leaves and other organic litter, grind it in the gizzard and void it as casts, converting large pieces of organic matter into rich humus and so improving soil fertility — their casts carry roughly 40 per cent more humus than the top nine inches of the soil they live in. Their burrowing also loosens, aerates and drains the soil, which is why Indian farmers call them the farmer's friend and why Charles Darwin devoted his last book (1881) to them, writing that 'it may be doubted whether there are many other animals which have played so important a part in the history of the world, as have these lowly organized creatures'. Statement 2 fails on the number. An earthworm does not have a single heart, but neither does it have two pairs: in the standard description of earthworm anatomy a pair of muscular aortic arches rings the coelom in each of segments seven to eleven and acts as hearts, pumping blood into the ventral vessel — five pairs, not two. Since only statement 1 stands, the answer is Only 1.

Why the other options are wrong — (a) This is the exact inversion of the truth. It rejects the one statement that is beyond dispute — the earthworm's role in building soil fertility — and keeps the one that is wrong on its number.  (b) Tempting, because statement 1 is obviously true and statement 2 sounds like a textbook detail. But the anatomical claim is wrong: the aortic arches that serve as the earthworm's hearts are described as a pair in each of segments seven to eleven, i.e. five pairs, not two.  (c) Chosen by candidates who spot that statement 2 is wrong and then over-correct. Statement 1 is correct — improving soil structure and fertility is precisely what earthworms are famous for.

Concept: Earthworms are terrestrial annelids: segmented, burrowing invertebrates that feed on dead and decaying organic matter, which makes them detritivores rather than decomposers in the microbial sense — they fragment litter and pass it through the gut, and microbes finish the mineralisation. They have a closed circulatory system, in which blood stays inside vessels: a dorsal and a ventral longitudinal vessel are linked by muscular aortic arches that contract like hearts. Ecologically they are classic 'ecosystem engineers' — their burrows aerate and drain the soil and their casts return nutrients to it.

State PCS 2025 Q21 — Science & Technology PYQ with Answer

State PCS 2025 Q21 — Science & Technology PYQ with Answer