SSC CPO 2025 PYQ — Question 161

SSC CPO - 9 Dec 2025 - Shift 1 • English • Q161

Which of the given options arranges the following sentences in the most logical sequence to form a meaningful paragraph?

1. Without keystone species, entire ecosystems can collapse, leading to significant biodiversity loss.
2. The concept of a keystone species was first introduced by ecologist Robert Paine, who studied the effect of removing certain predators from an ecosystem.
3. Keystone species play a disproportionately large role in maintaining the structure and stability of their ecosystems.
4. For example, sea otters help regulate sea urchin populations, preventing the destruction of kelp forests.
5. This idea revolutionized ecology by highlighting how some species have a far greater impact on their environment than others.

Show answer & explanation

Correct answer: B

Explanation

3-2-5-4-1

Explanation:

3 → Starts by defining keystone species (general statement).

2 → Then gives origin/history (Robert Paine).

5 → Explains the importance of the idea.

4 → Provides an example (sea otters).

1 → Concludes with the consequence (ecosystem collapse).