Which of the following is the primary source of energy for all ecosystems?
Answer: A
Solar radiation is the ultimate source of energy for all ecosystems. Plants capture this energy through photosynthesis, which forms the base of all food chains.
Q.2Easy
What is the approximate percentage of solar energy fixed by plants during photosynthesis?
Answer: A
Only 1-5% of incident solar radiation is actually fixed by plants through photosynthesis. The rest is either reflected or absorbed as heat.
Q.3Medium
The 10% law of energy transfer in an ecosystem states that only 10% of energy is transferred to the next trophic level. What happens to the remaining 90%?
Answer: B
The remaining 90% energy is lost through cellular respiration, heat dissipation, and decomposition processes at each trophic level, which is why ecosystems have fewer organisms at higher trophic levels.
Q.4Easy
Which type of succession occurs on bare rock or newly formed volcanic islands?
Answer: B
Primary succession occurs on areas with no pre-existing soil, such as bare rock or new volcanic islands. Pioneer species like lichens initiate the process.
Q.5Easy
Which organism is considered a pioneer species in primary succession?
Answer: B
Lichens are classic pioneer species in primary succession as they can colonize bare rock, secrete acids to break it down, and create conditions for soil formation.
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Q.6Medium
The concept of 'ecological niche' refers to:
Answer: B
An ecological niche encompasses the organism's habitat, food, behavior, and role in the ecosystem - essentially its complete functional position in the environment.
Q.7Easy
Which of the following biomes receives the least amount of rainfall annually?
Answer: C
Deserts receive less than 25 cm (10 inches) of rainfall annually, making them the driest biomes on Earth.
Q.8Medium
Which of the following is a characteristic of r-selected species?
Answer: B
r-selected species (like rabbits and insects) have high reproductive rates, short generation times, and invest little in individual offspring care, prioritizing quantity over quality.
Q.9Medium
The carrying capacity of an environment is best defined as:
Answer: A
Carrying capacity (K) is the maximum population size that an environment can sustain indefinitely given available resources and environmental resistance.
Q.10Medium
In India's biodiversity hotspots, which region is NOT included in the recognized biodiversity hotspots?
Answer: D
India has 4 recognized biodiversity hotspots: Western Ghats, Indo-Burma, Himalayas, and Sundaland. Eastern plains are not recognized as a separate hotspot.
Q.11Medium
The concept of 'biomagnification' refers to:
Answer: B
Biomagnification is the process where toxic pollutants (like DDT, mercury) accumulate in higher concentrations in organisms at higher trophic levels due to bioaccumulation.
Q.12Easy
Which of the following is an example of a renewable resource?
Answer: C
Solar energy is a renewable resource that can be naturally replenished. Coal, petroleum, and natural gas are non-renewable fossil fuels.
Q.13Medium
The process by which nitrogen is converted from atmospheric N₂ to usable forms by microorganisms is called:
Answer: B
Nitrogen fixation is the conversion of atmospheric N₂ to ammonia (NH₃) or nitrates by nitrogen-fixing bacteria like Rhizobium and Azospirillum.
Q.14Medium
Which of the following best describes 'eutrophication'?
Answer: B
Eutrophication is the over-enrichment of water with nutrients (phosphates and nitrates), leading to excessive algal growth, dead zones, and oxygen depletion.
Q.15Easy
Which gas is primarily responsible for the greenhouse effect and climate change?
Answer: C
Carbon dioxide (CO₂) is the primary greenhouse gas responsible for global warming, accounting for about 75% of anthropogenic greenhouse gas emissions.
Q.16Easy
A predator-prey relationship demonstrates which type of ecological interaction?
Answer: D
Predation is an ecological interaction where one organism (predator) hunts and consumes another (prey) for energy and nutrients.
Q.17Medium
Which of the following is a density-independent factor affecting population dynamics?
Answer: C
Drought is a density-independent (abiotic) factor because its effect on population is not influenced by population density. It equally affects all populations regardless of density.
Q.18Hard
The biodiversity of India is attributed primarily to:
Answer: B
India's exceptional biodiversity is due to its diverse climatic zones (tropical to alpine), varied topography, monsoon patterns, and complex geological history creating multiple ecological niches.
Q.19Hard
Which of the following phenomena is an example of positive feedback in an ecosystem?
Answer: B
Climate warming → permafrost thaw → CO₂ release → more warming is a positive feedback loop that amplifies the initial change, unlike negative feedback which stabilizes systems.
Q.20Medium
A forest ecosystem in the Western Ghats shows a decline in apex predator population, leading to an increase in herbivore numbers and subsequent overgrazing. Which ecological principle is being violated in this scenario?
Answer: D
The carrying capacity of the ecosystem is being exceeded due to removal of natural predators. Herbivore populations exceed the ecosystem's ability to sustain them without degradation, violating the carrying capacity principle. This leads to overgrazing and ecosystem destabilization.
