Ecosystem
Test 3

Correct answer Carries: 4.

Wrong Answer Carries: -1.

Which of the following best describes the detritus food chain?

Begins with living plants
Starts with dead organic matter
Does not include decomposers
Includes only primary consumers
2

The detritus food chain begins with dead organic matter, which is decomposed by microorganisms before passing through different consumers.

Which of the following represents the correct sequence of trophic levels in an ecosystem?

Producers → Primary consumers → Secondary consumers → Decomposers
Producers → Secondary consumers → Primary consumers → Decomposers
Decomposers → Producers → Primary consumers → Secondary consumers
Primary consumers → Secondary consumers → Producers → Decomposers
1

The correct sequence follows the energy flow: Producers are eaten by primary consumers, which are consumed by secondary consumers, and decomposers break down organic matter.

Which trophic level is occupied by primary carnivores in a grazing food chain?

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

Primary carnivores, such as frogs and small carnivorous animals, feed on herbivores and occupy the third trophic level in a grazing food chain.

Which of the following processes in decomposition results in the release of inorganic nutrients into the soil?

Humification
Leaching
Fragmentation
Mineralization
4

Mineralization is the final step in decomposition, where decomposers convert organic matter into inorganic nutrients.

Which of the following represents an inverted pyramid of biomass?

Grassland ecosystem
Forest ecosystem
Pond ecosystem
Desert ecosystem
3

In a pond ecosystem, the biomass of phytoplankton (producers) is lower than that of zooplankton (consumers), creating an inverted pyramid of biomass.

Which of the following statements about ecosystem productivity is correct?

Gross primary productivity (GPP) is always less than net primary productivity (NPP)
NPP is the energy available to herbivores
GPP does not include respiration loss
NPP is not influenced by environmental factors
2

Net primary productivity (NPP) is the energy available to herbivores after subtracting respiration loss from GPP.

Which of the following statements about the detritus food chain is correct?

It begins with dead organic matter
It excludes decomposers
It does not contribute to energy flow
It starts with living producers
1

The detritus food chain starts with dead organic matter, which is broken down by decomposers before being utilized by other organisms.

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

Energy flows in a unidirectional manner
Energy is lost as heat at each trophic level
Energy is fully transferred from one trophic level to the next
Producers capture energy from sunlight
3

Energy transfer between trophic levels is not 100% efficient; most energy is lost as heat.

Which of the following statements about biological magnification is incorrect?

Toxins accumulate at higher trophic levels
It affects top predators the most
Toxic substances decrease in concentration as they move up the food chain
Human activities contribute to biological magnification
3

Toxic substances increase in concentration as they move up the food chain, affecting top predators the most.

What term describes the total biomass produced by plants through photosynthesis?

Gross Primary Productivity (GPP)
Net Primary Productivity (NPP)
Secondary Productivity
Trophic efficiency
1

Gross Primary Productivity (GPP) is the total biomass produced by plants before respiration losses are deducted.

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