Biodiversity forms the basis for human existence in the following ways: Select the correct answer using the codes given below:

Answer: (d) 1, 2, 3 and 4

All four are ecosystem services that depend on biodiversity.

Statement by statement

1. ✓ CORRECT Microbes, fungi and earthworms build soil from rock and dead matter.

2. ✓ CORRECT Roots and ground cover bind soil against wind and rain.

3. ✓ CORRECT Decomposers recycle waste back into nutrients.

4. ✓ CORRECT Bees and other pollinators are needed for about three-quarters of food crop types.

The idea

Biodiversity is not a list of species to admire. Each group of organisms does a job that people depend on and cannot easily replace with machines.

Microbes, fungi, earthworms → make soil → Plant roots and ground cover → hold soil → Decomposers → recycle waste into nutrients → Bees, butterflies, birds, bats → pollinate crops

The trap

“all of the above” is right because every item is a real service.

Elimination technique

All four are plain, well-known benefits with no absolute word. Plain items of this kind are usually correct in Environment PYQs, which points to all four.

Also know

A useful image is the rivet popper idea of Paul Ehrlich: species are like the rivets of an aeroplane. Losing a few seems harmless, but each loss weakens the plane, and at some point it fails.