Ecosystem Chapter-Wise Test 16

Correct answer Carries: 4.

Wrong Answer Carries: -1.

Which of the following best describes an ecological pyramid?

A diagram representing the number, biomass, or energy at each trophic level
A representation of nutrient cycling
A model showing the interdependence of organisms
A classification system for food webs
1

Ecological pyramids represent the relative number, biomass, or energy of organisms at different trophic levels in an ecosystem.

Which of the following processes is responsible for the formation of humus?

Leaching
Humification
Catabolism
Fragmentation
2

Humification results in the formation of humus, a dark-colored, stable organic substance that is resistant to microbial degradation.

What is the role of leaching in decomposition?

It converts detritus into inorganic substances
It removes water-soluble inorganic nutrients
It releases enzymes for degradation
It increases humus formation
2

Leaching is the process by which water-soluble inorganic nutrients dissolve and percolate into the soil.

Which of the following statements about net primary productivity (NPP) is correct?

NPP is the total energy captured by plants
NPP is always greater than gross primary productivity (GPP)
NPP is the energy available to herbivores
NPP includes the energy lost during respiration
3

NPP is the energy available to herbivores after accounting for the energy used in respiration by plants.

What is the main source of energy for an ecosystem?

Chemical energy
Solar energy
Geothermal energy
Energy from decomposers
2

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

Which of the following is an incorrect statement about biological magnification?

Toxins accumulate at higher trophic levels
Top predators are the most affected
Toxins decrease in concentration as they move up the food chain
Human activities contribute to biological magnification
3

Toxins increase in concentration as they move up the food chain, a process known as biomagnification.

Which of the following is a correct statement about the nitrogen cycle?

Plants directly absorb nitrogen gas from the air
Denitrification converts nitrates into nitrogen gas
Nitrogen fixation releases nitrogen gas into the atmosphere
Animals directly fix atmospheric nitrogen
2

Denitrification is a microbial process that converts nitrates into nitrogen gas, returning it to the atmosphere.

Which trophic level do secondary consumers occupy in a food chain?

First trophic level
Second trophic level
Third trophic level
Fourth trophic level
3

Secondary consumers occupy the third trophic level in a food chain, feeding on primary consumers.

What is the role of fungi in the decomposition process?

Fix atmospheric nitrogen
Break down organic matter into simpler substances
Release oxygen into the atmosphere
Convert inorganic nutrients into organic matter
2

Fungi decompose complex organic matter into simpler substances, playing a crucial role in nutrient recycling.

Which of the following statements is true about the second law of thermodynamics in an ecosystem?

Energy is fully transferred between trophic levels
Energy is destroyed during metabolic processes
Energy is lost as heat at each trophic level
Energy cycles repeatedly in an ecosystem
3

The second law of thermodynamics states that energy transfer is inefficient, leading to energy loss as heat at each trophic level.

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