Ecosystem
Test 1

Correct answer Carries: 4.

Wrong Answer Carries: -1.

Which of the following best defines an ecosystem?

A collection of only abiotic components
A community of only biotic components
An interaction between biotic and abiotic components
A system that does not involve energy flow
3

An ecosystem consists of both biotic (living) and abiotic (non-living) components interacting with each other.

Which of the following describes a grazing food chain?

Starts with detritus and decomposers
Begins with living producers
Includes only carnivores
Does not involve energy transfer
2

A grazing food chain begins with living producers such as plants or phytoplankton, which are consumed by herbivores.

Which of the following is the best example of a self-sustaining ecosystem?

Crop field
Forest
Aquarium
Zoo
2

A forest is a self-sustaining ecosystem where biotic and abiotic components interact without human intervention.

What is the major role of decomposers in an ecosystem?

To fix atmospheric nitrogen
To break down organic matter into inorganic nutrients
To capture solar energy
To act as primary consumers
2

Decomposers break down organic matter into inorganic nutrients, which are then recycled back into the ecosystem.

Which component of an ecosystem is responsible for the conversion of organic matter into inorganic nutrients?

Producers
Consumers
Decomposers
Herbivores
3

Decomposers break down dead organic matter and release inorganic nutrients back into the soil, making them available for plants.

Which of the following is an incorrect statement about the nitrogen cycle?

Nitrogen fixation converts atmospheric nitrogen into usable forms
Denitrification releases nitrogen gas back into the atmosphere
Plants absorb nitrogen directly from the atmosphere
Decomposers release nitrogen from organic matter into the soil
3

Plants cannot absorb nitrogen directly from the atmosphere; they rely on nitrogen-fixing bacteria to convert nitrogen into usable forms.

Which of the following statements about the energy pyramid is correct?

It can be inverted in some ecosystems
It is always upright
It represents only the number of organisms
It shows that energy increases at higher trophic levels
2

The energy pyramid is always upright because energy is lost as heat at each trophic level.

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

NPP is the energy available to herbivores
NPP is always greater than gross primary productivity (GPP)
NPP accounts for energy lost in respiration
NPP is influenced by environmental factors
2

NPP is always less than GPP because it accounts for the energy used in respiration by plants.

Which of the following statements about trophic levels is correct?

Producers occupy the highest trophic level
Herbivores belong to the second trophic level
Energy increases as we move up the trophic levels
Carnivores belong to the first trophic level
2

Herbivores are primary consumers that feed on producers and occupy the second trophic level.

Which trophic level do primary consumers belong to?

First
Second
Third
Fourth
2

Primary consumers (herbivores) feed on producers (plants) and occupy the second trophic level.

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