'Aerial metagenomics' best refers to which one of the following situations?

(a) Collecting DNA samples from air in a habitat at one go ✓ UPSC's answer
(b) Understanding the genetic makeup of avian species of a habitat
(c) Using air-borne devices to collect blood samples from moving animals
(d) Sending drones to inaccessible areas to collect plant and animal samples from land surfaces and water bodies

Why the answer is (a)

• Metagenomics sequences all the genetic material in an environmental sample at once, without culturing individual organisms.

• 'Aerial metagenomics' or airborne environmental DNA (eDNA) sampling filters air from a habitat and sequences the DNA it carries — shed skin, hair, pollen and spores — to detect which species are present, in one sweep — option (a).

• Studies in 2022 detected dozens of animal species at zoos from air samples alone, opening a non-invasive way to survey biodiversity.

• Option (b) describes bird genetics, and options (c) and (d) describe drone-based physical sampling; none captures the idea of sequencing DNA from the air.

• Hence option (a).

Why the other options are wrong

(b) Understanding the genetic makeup of avian species of a habitat: 'Aerial' refers to air sampling, not to birds.
(c) Using air-borne devices to collect blood samples from moving animals: It involves no blood sampling or devices chasing animals.
(d) Sending drones to inaccessible areas to collect plant and animal samples from land…: It is not drone collection of physical specimens.

Asked in the GS Paper I of the UPSC Civil Services Preliminary Examination 2023, held on 28 May 2023. Question and answer key: Union Public Service Commission. Explanation: UPSC Answer Check.