UPSC Prelims 2019 Q28: Environment & Ecology – Ecosystems & Ecology Concepts
- (a) 1 and 3 only
- (b) 2, 3 and 4 only
- (c) 2 and 4 only
- (d) 1, 2, 3 and 4
Answer: (d) 1, 2, 3 and 4
Explanation
Herbivory and Viviparity Across Vertebrates
| Statement | Claim | Verdict | Example |
|---|---|---|---|
| 1 | Some turtles are herbivores | TRUE | Green sea turtle (adults), tortoises are herbivorous - feed on seagrass, algae, plants. |
| 2 | Some fish are herbivores | TRUE | Parrotfish, surgeonfish, grass carp - all herbivorous fish grazing on algae/aquatic plants. |
| 3 | Some marine mammals are herbivores | TRUE | Dugongs and manatees (Sirenia) are strictly herbivorous - feed on seagrass. |
| 4 | Some snakes are viviparous | TRUE | Boas, sea snakes, pit vipers give birth to live young (viviparous or ovoviviparous). |
All four statements are correct. Answer: (d) 1, 2, 3 and 4.
Answer: (d) 1, 2, 3 and 4.
Why each option is right or wrong
- (a) Incorrect. Statements 2 and 4 are also correct.
- (b) Incorrect. Statement 1 is also correct - some turtles are herbivorous.
- (c) Incorrect. Statements 1 and 3 are also correct.
- (d) CORRECT. All four - herbivorous turtles, herbivorous fish, herbivorous marine mammals (dugong/manatee), and viviparous snakes (boas, sea snakes) - are documented.
Key point
All four are true: herbivorous turtles (green turtle, tortoises), herbivorous fish (parrotfish, grass carp), herbivorous marine mammals (dugong, manatee), viviparous snakes (boas, sea snakes).
Remember
All four statements are correct - some turtles (green sea turtle, tortoises), some fish (parrotfish, grass carp), and some marine mammals (dugongs, manatees) are herbivores; and some snakes (boas, sea snakes, pit vipers) are viviparous, giving birth to live young.
Common mistakes
- Assuming all snakes lay eggs - only ~70% of snakes are oviparous; the rest are viviparous or ovoviviparous.
- Confusing dolphins/whales (carnivorous) with dugongs/manatees (herbivorous).
- Not knowing that the green sea turtle is one of the few sea turtles that is herbivorous as an adult.
Exam tip
Marine mammals herbivore vs carnivore: Sirenia (dugongs, manatees) = only herbivorous marine mammals. Cetaceans (whales, dolphins), Pinnipeds (seals, sea lions), Sea otters = carnivorous/omnivorous.
Sources
- NCERT Class 11 - Biology (Kingdom Animalia)
- IUCN species accounts - Sirenia and reptile reproduction