Biota, Environment, and Conservation

(a) River dolphin

The Gangetic river dolphin (Platanista gangetica) was declared India's National Aquatic Animal in 2009. It is an indicator of river-ecosystem health. Blue whale and sea horse are marine and not national symbols; "Gangetic shark" is a freshwater shark, not the national aquatic animal.

(b) Habitat loss and fragmentation

Habitat loss and fragmentation is the most important cause of extinction (e.g. Amazon rainforest clearing). Alien invasion, co-extinction and over-exploitation are real causes but each is less significant globally.

(d) 34

Norman Myers and later Conservation International identified 34 biodiversity hotspots worldwide (25 in his earlier list). Three of them, Western Ghats and Sri Lanka, Indo-Burma and Himalaya, cover parts of India.

(a) Dachigam National Park, Jammu & Kashmir

Hangul (Kashmir stag, Cervus elaphus hanglu) is found in Dachigam National Park. Keibul Lamjao is home to the sangai (brow-antlered deer) on its floating phumdis, and Bandhavgarh is known for tigers.

(c) seagull

Biomagnification increases DDT concentration at each trophic level, so the top consumer in the aquatic food chain (the seagull) has the highest concentration, while phytoplankton has the lowest.

(c) Endemic

An endemic species is restricted to a particular geographic region and found nowhere else. A keystone species has a disproportionate ecological role, an alien species is introduced from elsewhere, and a rare species simply has few individuals.

(c) IUCN

The International Union for Conservation of Nature and Natural Resources publishes the Red List of threatened species. WWF is a conservation NGO, ICFRE is Indian forestry research, and UNEP is the UN environment programme.

(d) Critically Endangered

IUCN uses "Critically Endangered" for a species facing an extremely high risk of extinction in the wild in the immediate future. "Vulnerable" is a lower risk category, "Extinct" means no living individual remains, and "Endemic" only means restricted to a particular area.

(c) Seed Bank

Ex situ conservation protects species outside their natural habitat, such as in seed banks, zoos, botanical gardens and gene banks. Sacred groves, national parks and wildlife sanctuaries are in situ methods, conserving organisms in their natural habitat.

(c) Protect and conserve the whole ecosystem

In-situ conservation protects species in their natural habitat, so the entire ecosystem is conserved (national parks, sanctuaries, biosphere reserves). Options limited to endangered, extinct or high-risk species describe only part of it; extinct species cannot be conserved at all.

(d) Fragmentation

Detritivores such as earthworms break detritus into smaller particles; this first step of decomposition is called fragmentation. Humification and catabolism come later, and decomposition is the whole process, not just this step.

(b) Statement I is incorrect but Statement II is correct

Passing exhaust through electrode wires that charge dust particles describes an electrostatic precipitator, not a scrubber. A scrubber removes gases like SO$_2$ but not fine particulates such as PM 2.5, which an electrostatic precipitator removes efficiently.

(b) Biomagnification refers to increase in concentration of the toxicant at successive trophic levels.

Biomagnification is the rise in toxicant concentration along successive trophic levels. Eutrophication is nutrient enrichment of water (not sewage increase per se), nutrient excess promotes algal bloom, and algal bloom increases fish mortality.

(a) A-I, B-II, C-III, D-IV

Leopard and lion compete for prey; cuckoo laying eggs in a crow's nest is brood parasitism; mycorrhizae is mutualism; the cattle egret benefits from cattle without affecting them, which is commensalism.

(c) Statement I is correct but Statement II is incorrect

The electrostatic precipitator is the most widely used device in thermal power plants and removes particulate matter by charging dust particles. It does not remove ionising radiation.

(a) Statement I is false but Statement II is true

Gause's principle says that two closely related species competing for the same (not different) limiting resources cannot coexist indefinitely, and the inferior competitor is eliminated. So Statement I is false because of "different resources", and Statement II is true.

(d) $(\mathrm{KCal\ m^{-2})\ yr^{-1}}$

Productivity is the rate of biomass or energy production, so it needs a time component. It is expressed as $\mathrm{g\,m^{-2}\,yr^{-1}}$ or $(\mathrm{kcal\,m^{-2})\,yr^{-1}}$. Options (a)-(c) have no time term and describe standing crop or amount, not a rate.

(d) Statement I is incorrect but Statement II is correct

Statement II is correct: the fig and its wasp show an obligate mutualism. The wasp pollinates the fig and lays eggs in its ovaries, so it completes its life cycle inside the fruit. Statement I is incorrect because a fig is a plant product and the wasps are not "enclosed" food; calling it non-vegetarian is not a scientific statement.

(b) A-III, B-I, C-II, D-IV

The Evil Quartet is the four main causes of biodiversity loss. Ex situ conservation includes cryopreservation of gametes. Lantana camara is an alien invasive species, and the Dodo is an extinct bird.

(c) Statement I is correct but Statement II is incorrect

Energy flow is unidirectional from the sun to producers and then to consumers, and it cannot be recycled. Ecosystems are not exempt from the second law of thermodynamics; they need a continuous input of energy to offset the entropy that increases as energy is dissipated as heat.