Ecosystem Chapter-Wise Test 11

Correct answer Carries: 4.

Wrong Answer Carries: -1.

What is the primary role of decomposers in an ecosystem?

Convert inorganic substances into organic matter
Break down dead organic matter and recycle nutrients
Fix atmospheric nitrogen into the soil
Consume producers for energy
2

Decomposers break down dead organic matter into simpler substances, playing a crucial role in nutrient cycling.

What is the role of nitrifying bacteria in the nitrogen cycle?

Convert ammonia into nitrates
Fix atmospheric nitrogen
Release nitrogen gas into the atmosphere
Decompose organic matter
1

Nitrifying bacteria, such as Nitrosomonas and Nitrobacter, convert ammonia into nitrates, making nitrogen available for plant use.

Which of the following statements about primary productivity is incorrect?

Primary productivity is influenced by sunlight and nutrients
Net primary productivity (NPP) is always greater than gross primary productivity (GPP)
GPP includes the total energy captured by plants
NPP is the energy available for herbivores
2

Net primary productivity (NPP) is always less than gross primary productivity (GPP) because NPP accounts for respiration loss.

Which of the following is a major limiting factor for productivity in aquatic ecosystems?

Carbon dioxide availability
Light and nutrient availability
Temperature stability
Oxygen content
2

Light and nutrient availability are the primary limiting factors in aquatic ecosystems, affecting photosynthesis and primary productivity.

Why does an energy pyramid remain upright?

Energy is completely transferred between trophic levels
Energy is lost as heat at each trophic level
Consumers store more energy than producers
Energy cycles continuously between trophic levels
2

Energy is lost as heat at each trophic level, making the energy pyramid always upright and unidirectional.

Which of the following is an example of a secondary consumer?

Grass
Rabbit
Frog
Hawk
3

A frog is a secondary consumer as it feeds on primary consumers like insects.

Which of the following statements about food chains is incorrect?

They represent energy flow in an ecosystem
Each organism in the chain occupies a specific trophic level
Energy transfer is 100% efficient between trophic levels
They include producers and consumers
3

Energy transfer between trophic levels is not 100% efficient; only about 10% of energy is passed on, with the rest lost as heat.

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

Energy flow is unidirectional
Energy decreases at higher trophic levels
Energy is lost as heat at each level
Energy cycles through the ecosystem
4

Energy does not cycle in an ecosystem; it flows in one direction from producers to consumers and is lost as heat.

Which of the following organisms plays a key role in nitrogen fixation?

Fungi
Rhizobium bacteria
Earthworms
Zooplankton
2

Rhizobium bacteria, found in the root nodules of leguminous plants, fix atmospheric nitrogen into a usable form for plants.

Which of the following statements about ecological pyramids is incorrect?

Pyramids of energy are always upright
Pyramids of biomass in aquatic ecosystems are often inverted
Pyramids of number are always upright
Pyramids represent energy, biomass, or numbers in an ecosystem
3

The pyramid of number is not always upright; in forests, a single tree supports many herbivores, causing an inverted pyramid.

Performance Summary

Score:

Category Details
Total Attempts:
Total Skipped:
Total Wrong Answers:
Total Correct Answers:
Time Taken:
Average Time Taken per Question:
Accuracy:
0