Free printable worksheet
Class 9 · Science and Technology · 10 Aug 2026
According to the 10 percent law of energy transfer in an ecosystem, approximately what percentage of food energy is available to the next trophic level from the preceding one?
[1 mark]How does the introduction of an invasive alien species, such as Lantana camara in Indian forests, typically affect local ecological balance?
[2 marks]Match each ecological term from Indian wildlife studies with its correct trophic description.
[2 marks]| Column A | Column B |
|---|---|
| 1. Grass | a. Primary Producer |
| 2. Grasshopper | b. Primary Consumer |
| 3. Frog | c. Secondary Consumer |
| 4. Snake | d. Tertiary Consumer |
Answer: __________________________________________
Match each ecological term in the left column with its correct definition or example in the right column.
[2 marks]| Column A | Column B |
|---|---|
| 1. Keystone Species | a. A species with a disproportionately large effect on its ecosystem |
| 2. Climax Community | b. The final stable stage of ecological succession |
| 3. Eutrophication | c. Nutrient enrichment leading to algal blooms and oxygen depletion |
| 4. Endemic Species | d. Species restricted to a specific geographic region like the Western Ghats |
Answer: __________________________________________
Match the ecological terms in Column A with their correct descriptions in Column B.
[2 marks]| Column A | Column B |
|---|---|
| 1. Climax Community | a. The final stable community in ecological succession |
| 2. Producer | b. Autotrophic organism that fixes solar energy |
| 3. Keystone Species | c. Species that has a disproportionately large effect on its ecosystem |
| 4. Biomagnification | d. Concentration of toxins increasing along a food chain |
Answer: __________________________________________
In a typical grassland food chain in the Terai region, primary consumers directly feed upon green plants and are known as _____, while organisms that break down dead organic matter are called _____.
[2 marks]The natural process by which an ecological community gradually changes and develops toward a stable climax community is called ecological _____.
[1 mark]In an aquatic ecosystem, excess runoff of agricultural fertilizers containing nitrates and phosphates causes rapid phytoplankton growth, a process known as _____, which ultimately reduces dissolved _____ levels.
[3 marks]Define the term 'trophic level' in the context of an ecosystem.
[2 marks]State the primary role of apex predators in maintaining ecological balance in a wildlife sanctuary like Jim Corbett National Park.
[2 marks]List the two main laws of thermodynamics that govern the flow of energy through living ecosystems.
[2 marks]List two anthropogenic activities that frequently disrupt ecological balance in Indian wetlands, and briefly state their immediate environmental impact.
[2 marks]Explain how the introduction of an invasive alien species, such as water hyacinth (Eichhornia crassipes) in a local wetland in West Bengal, can disrupt ecological balance.
[3 marks]Analyze the potential ecological consequences of removing an apex predator, such as the Bengal tiger, from a forest ecosystem food web. Support your answer with concepts of trophic cascades.
[5 marks]In a freshwater pond ecosystem in Kerala, phytoplankton fix 10,000 Joules of solar energy. Calculate the amount of energy available to the tertiary consumer (e.g., a carnivorous fish) in the food chain: Phytoplankton -> Zooplankton -> Small Fish -> Large Carnivorous Fish. Show your calculations clearly.
[3 marks]Identify the trophic levels in a typical aquatic pond food chain represented by the reference diagram.
[3 marks]Identify the missing trophic labels in the standard ecological pyramid of energy from base to top.
[3 marks]