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Study the four statements (a–d) given below and select the two correct ones out of them.
(a) A lion eating a deer and a sparrow feeding on grain are ecologically similar in being consumers
(b) Predator star fish $Pisaster$ helps in maintaining species diversity of some invertebrates
(c) Predators ultimately lead to the extinction of prey species
(d) Production of chemicals such as nicotine, strychnine by the plants are metabolic disorders
The two correct statements are
(a) A lion eating a deer and a sparrow feeding on grain are ecologically similar in being consumers
(b) Predator star fish $Pisaster$ helps in maintaining species diversity of some invertebrates
(c) Predators ultimately lead to the extinction of prey species
(d) Production of chemicals such as nicotine, strychnine by the plants are metabolic disorders
The two correct statements are
A
(a) and (b)
B
(b) and (c)
C
(c) and (d)
D
(a) and (d)
Detailed Solution
(a) is correct: both the lion (a carnivore) and the sparrow feeding on grain (a herbivore) depend on other organisms for food, so ecologically both are consumers.
(b) is correct: in the rocky intertidal communities of the American Pacific coast, the starfish $Pisaster$ is an important predator; when it was removed experimentally, more than 10 species of invertebrates became extinct within a year because of interspecific competition. So it maintains species diversity.
(c) is wrong: predators in nature are 'prudent'; if a predator over-exploited its prey, the prey would become extinct and the predator would follow. Prey species have also evolved defences.
(d) is wrong: nicotine, strychnine, caffeine, quinine and opium are chemicals produced by plants as defences against grazers and browsers; they are not metabolic disorders.
Hence the two correct statements are (a) and (b).
(b) is correct: in the rocky intertidal communities of the American Pacific coast, the starfish $Pisaster$ is an important predator; when it was removed experimentally, more than 10 species of invertebrates became extinct within a year because of interspecific competition. So it maintains species diversity.
(c) is wrong: predators in nature are 'prudent'; if a predator over-exploited its prey, the prey would become extinct and the predator would follow. Prey species have also evolved defences.
(d) is wrong: nicotine, strychnine, caffeine, quinine and opium are chemicals produced by plants as defences against grazers and browsers; they are not metabolic disorders.
Hence the two correct statements are (a) and (b).