Ecosystem Chapter-Wise Test 21

Correct answer Carries: 4.

Wrong Answer Carries: -1.

Which of the following statements about the role of decomposers is correct?

Decomposers convert organic matter into inorganic substances
Decomposers store nutrients permanently
Decomposers do not contribute to nutrient cycling
Decomposers absorb atmospheric nitrogen directly
1

Decomposers break down organic matter into inorganic substances, releasing nutrients back into the environment.

Which trophic level has the least energy available to it?

Producers
Primary consumers
Secondary consumers
Tertiary consumers
4

Tertiary consumers occupy the highest trophic level and receive the least energy due to energy loss at each transfer.

Which of the following is a man-made ecosystem?

Grassland
Pond
Aquarium
Forest
3

An aquarium is a man-made ecosystem where biotic and abiotic components are artificially maintained.

Which of the following ecological pyramids can be inverted in an aquatic ecosystem?

Pyramid of number
Pyramid of energy
Pyramid of biomass
Both 1 and 3
3

In aquatic ecosystems, the pyramid of biomass is often inverted because the biomass of producers (phytoplankton) is smaller than that of consumers.

Which of the following correctly represents net primary productivity (NPP)?

NPP = GPP - R
NPP = GPP + R
NPP = R - GPP
NPP = GPP × R
1

Net Primary Productivity (NPP) is the amount of energy left after plants use some for respiration (R), calculated as NPP = GPP - R.

Which of the following statements about food chains is correct?

Food chains always start with decomposers
Energy is lost as heat at each trophic level
Food chains are always independent of each other
All energy in a food chain is transferred to the next level
2

Energy is lost as heat at each trophic level, following the second law of thermodynamics.

What is the primary source of energy in most ecosystems?

Wind energy
Solar energy
Geothermal energy
Chemical energy
2

Solar energy is the primary source of energy for most ecosystems, driving photosynthesis and energy flow through food chains.

What is the main reason for the low primary productivity of oceans despite covering 70% of the Earth's surface?

Lack of sunlight
Low nutrient availability
High consumer population
Limited producer diversity
2

Despite their vast area, oceans have low productivity due to the limited availability of essential nutrients in deep waters.

Which of the following is an incorrect statement about trophic levels?

Producers occupy the first trophic level
Herbivores belong to the second trophic level
Carnivores belong to the first trophic level
Energy flow decreases at higher trophic levels
3

Carnivores do not belong to the first trophic level; they are secondary or tertiary consumers.

Which of the following is an incorrect statement about food webs?

Food webs consist of multiple interconnected food chains
Food webs exclude decomposers
Food webs show complex feeding relationships
Food webs help maintain ecosystem balance
2

Food webs include decomposers, which play a crucial role in nutrient cycling and maintaining ecosystem balance.

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