Read the paragraph and answer the Question given below:
There is no natural habitat on earth known that is inhabited just by a single species. For any species, the minimal requirement is one more species on which it can feed. Even a plant species, which makes its own food, cannot survive alone and needs soil microbes to break down the organic matter in soil and return the inorganic nutrients for absorption. It is obvious that in nature, animals, plants and microbes do not and cannot live in isolation but interact in various ways to form a biological community.
Which of the following is correct among the following statements related to species interaction?
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → Predators help in maintaining species diversity in a community
Option (1) Calotropis releases a strong smell to prevent cattles and goats to eat its leaves — Incorrect. Calotropis protects itself with a chemical defence: it produces highly poisonous cardiac glycosides, and that is why cattle and goats do not browse on it. No smell is involved.
Option (2) Predators help in maintaining species diversity in a community — Correct. By reducing competition among prey species, a predator stops one strong prey species from wiping out the others.
Option (3) Totally unrelated species never compete for the same resource — Incorrect. Unrelated species can compete. In some shallow South American lakes, visiting flamingoes and resident fishes compete for the same food, the zooplankton.
Option (4) Closely related species competing for the same resources cannot co-exist indefinitely even if the resources are unlimited — Incorrect. This is Gause’s competitive exclusion principle, but it holds when resources are limiting. The words “even if the resources are unlimited” make it wrong.
Note: The passage is taken from NCERT. NTA has put lines of the NCERT text together to make it. Most CUET (UG) questions come straight from NCERT, so study the book line by line, including figures and their titles.
NCERT Extract:
Population Interactions – “… Predators also help in maintaining species diversity in a community, by reducing the intensity of competition among competing prey species. In the rocky intertidal communities of the American Pacific Coast the starfish Pisaster is an important predator. In a field experiment, when all the starfish were removed from an enclosed intertidal area, more than 10 species of invertebrates became extinct within a year, because of interspecific competition.”