Ecosystem
Test 4

Correct answer Carries: 4.

Wrong Answer Carries: -1.

Which process is responsible for the accumulation of a dark-colored amorphous substance in soil?

Leaching
Humification
Fragmentation
Mineralization
2

Humification leads to the accumulation of humus, a dark-colored amorphous substance that is resistant to microbial degradation.

Which of the following statements about primary productivity is correct?

It includes only the energy used by herbivores
It is influenced by environmental factors and nutrient availability
It remains constant in all ecosystems
It does not depend on sunlight
2

Primary productivity varies across ecosystems and is influenced by factors such as sunlight, nutrient availability, and temperature.

Which of the following correctly describes gross primary productivity (GPP)?

Total biomass produced by plants through photosynthesis
Energy available to herbivores after respiration
Total amount of energy lost as heat in an ecosystem
Rate of decomposition of organic matter
1

Gross primary productivity (GPP) is the total biomass or organic matter produced by plants through photosynthesis.

Which of the following best describes the role of primary producers in an ecosystem?

They break down dead organic matter
They convert inorganic substances into organic material
They obtain energy by consuming other organisms
They decompose organic waste
2

Primary producers, such as plants and phytoplankton, convert inorganic substances into organic material through photosynthesis.

Which of the following is a primary consumer in a grassland ecosystem?

Lion
Grass
Deer
Snake
3

Deer are herbivores that feed on grass and other plants, making them primary consumers in a grassland ecosystem.

Which of the following statements about energy flow in an ecosystem is correct?

Energy flow is cyclic and continuously recycled
Energy flows in a unidirectional manner
Energy increases at higher trophic levels
All energy at each trophic level is used for biomass production
2

Energy flows in a unidirectional manner from producers to consumers and is eventually lost as heat.

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

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

Denitrification is the process in which bacteria convert nitrates back into nitrogen gas, returning it to the atmosphere.

Which of the following statements about decomposition is incorrect?

Decomposition involves breakdown of organic matter
Decomposers release nutrients into the ecosystem
Humification leads to the formation of humus
Decomposition is faster in dry environments
4

Decomposition is slower in dry environments because moisture is essential for microbial activity.

Which of the following statements about detritivores is incorrect?

Detritivores feed on dead organic matter
Detritivores contribute to decomposition
Detritivores consume living plants
Earthworms and fungi are examples of detritivores
3

Detritivores feed on dead organic matter, not living plants.

Which of the following is NOT a category of ecosystems?

Terrestrial ecosystem
Aquatic ecosystem
Biotic ecosystem
Man-made ecosystem
3

Ecosystems are categorized as terrestrial, aquatic, and man-made. Biotic is a component of an ecosystem, not a category.

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