Read the passage carefully and give the answers to the next five questions:

Does the number of species in a community really matter to the functioning of the ecosystem? This is a question for which ecologists have not been able to give a definitive answer. For many decades, ecologists believed that communities with more species generally tend to be more stable than those with less species. According to the International Union for Conservation of Nature and Natural Resources (IUCN) (2004), the total number of plant and animal species described so far is more than 1.5 million.

Which of the following is not a characteristic of a stable biological community?

The correct option is: All the species are equally important in a stable community and the absence of any one leads to its unsustainability.

Explanation:

A stable biological community is characterized by specific ecological features that allow it to persist over time. According to ecological principles (such as those described by David Tilman and other ecologists), a stable community has the following key attributes:

1. Productivity Stability: The community should not show too much variation in its total biomass or productivity from year to year.
2. Resilience and Resistance: It must be either resistant or resilient to occasional disturbances, whether natural or man-made.
3. Invasion Resistance: It must be resistant to invasions by alien (exotic) species.

The statement "All the species are equally important in a stable community and the absence of any one leads to its unsustainability" is not a characteristic of a stable community. In any ecosystem, species do not play completely equal roles; some species, known as keystone species, have a much larger impact on community structure and functioning than others. Furthermore, stable communities often have functional redundancy, meaning multiple species perform similar ecological functions, so the loss of a single species does not automatically lead to the immediate collapse or unsustainability of the entire community.