Question 1

Consider the following statements regarding ecological succession: 1. Primary succession occurs on bare rock or newly formed land. 2. Secondary succession occurs in areas where communities have been disturbed but soil remains. 3. Climax community is the final stable stage of succession. Which of the statements given above is/are correct?

Accepted Answer

1, 2 and 3. All three statements are correct. Primary succession starts on barren surfaces, secondary succession occurs where soil is intact after disturbance, and climax community represents the stable endpoint of succession.

Question 2

Consider: 1. Primary productivity is highest in tropical rainforests. 2. Decomposers are essential for nutrient cycling. 3. Ecological pyramids are always upright for energy. Which correct?

Accepted Answer

All three. All correct. Tropical forests have highest productivity. Decomposers recycle nutrients. Energy pyramids are always upright (10% rule).

Question 3

Which one of the following is the correct sequence of ecosystems in the order of decreasing productivity?

Accepted Answer

Mangroves, grasslands, lakes, oceans. Mangroves have the highest productivity among the given options due to nutrient-rich coastal environments. The correct decreasing order is: Mangroves > Grasslands > Lakes > Oceans. Open oceans have the lowest per-unit-area productivity.

Question 4

Consider the following statements: 1. In a food chain, energy transfer from one trophic level to the next is approximately 10%. 2. Detritivores are part of the grazing food chain. 3. In aquatic ecosystems, the biomass pyramid is inverted. Which of the statements given above is/are correct?

Accepted Answer

1 and 3 only. The 10% rule (Lindeman's efficiency) states approximately 10% energy transfers between trophic levels. Detritivores are part of the detritus food chain, not grazing. In aquatic ecosystems, biomass pyramid can be inverted as producers (phytoplankton) have less biomass than consumers at any given time.

Question 5

With reference to the food chains in ecosystems, consider the following statements: 1. A food chain involves a nutritive interaction between living organisms. 2. In a parasitic food chain, the organisms become progressively smaller. 3. A food chain always begins with a green plant. Which of the statements given above is/are correct?

Accepted Answer

1 and 2 only. Statement 1 is correct as food chains show nutritive relationships. Statement 2 is correct as parasites are generally smaller than their hosts. Statement 3 is incorrect because detritus food chains begin with dead organic matter.

Question 6

In the context of ecosystem productivity, which of the following is/are correct? 1. Net Primary Productivity (NPP) equals Gross Primary Productivity minus Respiration. 2. Tropical rainforests have the highest net primary productivity among terrestrial ecosystems. 3. Deep ocean has higher productivity than estuaries.

Accepted Answer

1 and 2 only. NPP = GPP - Respiration is correct. Tropical rainforests have the highest terrestrial NPP. Estuaries are among the most productive ecosystems, far exceeding deep oceans which have very low productivity per unit area.

Question 7

How many of the following are examples of primary consumers in a grassland ecosystem? 1. Grasshopper 2. Frog 3. Deer 4. Rabbit

Accepted Answer

Only three. Primary consumers are herbivores that feed directly on plants. Grasshopper, Deer, and Rabbit are herbivores (primary consumers). Frog is a secondary consumer as it feeds on insects. So three of the four are primary consumers.

Question 8

Which of the following statements regarding biomes is/are correct? 1. Tundra biome has permafrost. 2. Taiga is dominated by coniferous forests. 3. Savanna receives more rainfall than tropical deciduous forests.

Accepted Answer

1 and 2 only. Tundra is characterized by permafrost (permanently frozen subsoil). Taiga (boreal forest) is dominated by conifers like spruce and pine. Savanna receives less rainfall (50-130 cm) than tropical deciduous forests (100-200 cm).

Question 9

Consider the following statements about biogeochemical cycles: 1. The phosphorus cycle does not have a gaseous phase. 2. Nitrogen fixation is carried out only by symbiotic bacteria. 3. Carbon cycle involves both oceanic and atmospheric reservoirs. Which of the statements given above is/are correct?

Accepted Answer

1 and 3 only. Phosphorus cycle is entirely sedimentary with no gaseous phase. Statement 2 is incorrect because free-living bacteria like Azotobacter also fix nitrogen, not just symbiotic ones like Rhizobium. Carbon cycle involves both oceanic and atmospheric reservoirs.

Question 10

With reference to ecosystem services, consider the following: 1. Pollination by bees is a provisioning service. 2. Carbon sequestration by forests is a regulating service. 3. Nutrient cycling is a supporting service. Which of the statements given above is/are correct?

Accepted Answer

2 and 3 only. Pollination is a regulating service, not provisioning. Provisioning services include food, water, timber. Carbon sequestration by forests is indeed a regulating service. Nutrient cycling is a supporting service as it supports other ecosystem functions.

Environment Previous Year Questions

Q2: Consider: 1. Primary productivity is highest in tropical rainforests. 2. Decomposers are essential for nutrient cycling. 3. Ecological pyramids are always upright for energy. Which correct?

Q3: Which one of the following is the correct sequence of ecosystems in the order of decreasing productivity?

Q4: Consider the following statements: 1. In a food chain, energy transfer from one trophic level to the next is approximately 10%. 2. Detritivores are part of the grazing food chain. 3. In aquatic ecosystems, the biomass pyramid is inverted. Which of the statements given above is/are correct?

Q7: How many of the following are examples of primary consumers in a grassland ecosystem? 1. Grasshopper 2. Frog 3. Deer 4. Rabbit

Q8: Which of the following statements regarding biomes is/are correct? 1. Tundra biome has permafrost. 2. Taiga is dominated by coniferous forests. 3. Savanna receives more rainfall than tropical deciduous forests.

Q10: With reference to ecosystem services, consider the following: 1. Pollination by bees is a provisioning service. 2. Carbon sequestration by forests is a regulating service. 3. Nutrient cycling is a supporting service. Which of the statements given above is/are correct?

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