Ecosystem MCQs

51. Which component regulates climate in an ecosystem?
A) Soil
B) Water
C) Atmosphere
D) Plants
Answer: C
Which gas is most important in photosynthesis?
A) Oxygen
B) Nitrogen
C) Carbon dioxide
D) Hydrogen
Answer: C
Which organism is both producer and consumer?
A) Algae
B) Euglena
C) Grass
D) Tree
Answer: B
The transfer of energy from one trophic level to another is called:
A) Cycling
B) Flow
C) Conversion
D) Absorption
Answer: B
Which level has the least energy?
A) Producers
B) Primary consumers
C) Secondary consumers
D) Tertiary consumers
Answer: D
Food chain always starts with:
A) Carnivores
B) Herbivores
C) Producers
D) Decomposers
Answer: C
The largest ecosystem on Earth is:
A) Forest
B) Ocean
C) Desert
D) Grassland
Answer: B
Which of the following is a terrestrial ecosystem?
A) Pond
B) Lake
C) Forest
D) Ocean
Answer: C
Which ecosystem has very low biodiversity?
A) Forest
B) Grassland
C) Desert
D) Wetland
Answer: C
Lichens are example of:
A) Consumers
B) Decomposers
C) Pioneer species
D) Parasites
Answer: C
Which cycle is most affected by deforestation?
A) Nitrogen cycle
B) Carbon cycle
C) Water cycle
D) Oxygen cycle
Answer: B
Which trophic level do humans belong to?
A) Producer
B) Primary consumer
C) Omnivore
D) Decomposer
Answer: C
Biomagnification occurs in:
A) Water cycle
B) Food chain
C) Soil
D) Atmosphere
Answer: B
The accumulation of toxic substances increases at:
A) Lower trophic levels
B) Higher trophic levels
C) Producer level
D) Decomposer level
Answer: B
Which of the following is not a renewable resource?
A) Solar energy
B) Wind energy
C) Coal
D) Water
Answer: C
Ecological pyramids show:
A) Energy only
B) Number, biomass, or energy
C) Water content
D) Temperature
Answer: B
The main source of nitrogen in ecosystems is:
A) Soil
B) Atmosphere
C) Plants
D) Animals
Answer: B
Denitrification converts:
A) Nitrogen to ammonia
B) Nitrates to nitrogen gas
C) Ammonia to nitrates
D) Nitrites to ammonia
Answer: B
Which process converts ammonia into nitrates?
A) Denitrification
B) Nitrogen fixation
C) Nitrification
D) Assimilation
Answer: C
Which ecosystem has maximum sunlight penetration?
A) Forest
B) Desert
C) Ocean surface
D) Deep sea
Answer: C
Phytoplankton are:
A) Producers
B) Consumers
C) Decomposers
D) Carnivores
Answer: A
Zooplankton are:
A) Producers
B) Primary consumers
C) Decomposers
D) Parasites
Answer: B
Which zone of ocean receives no sunlight?
A) Photic
B) Aphotic
C) Littoral
D) Pelagic
Answer: B
The littoral zone is found in:
A) Forest
B) Desert
C) Lakes
D) Mountains
Answer: C
Which ecosystem is most stable?
A) Desert
B) Forest
C) Grassland
D) Tundra
Answer: B
Carrying capacity refers to:
A) Population growth
B) Maximum population supported
C) Minimum population
D) Migration
Answer: B
Overgrazing leads to:
A) Increased fertility
B) Soil erosion
C) Water increase
D) Biodiversity increase
Answer: B
Deforestation results in:
A) Increased rainfall
B) Soil erosion
C) Cooling
D) Stability
Answer: B
Global warming is caused by:
A) Oxygen
B) Nitrogen
C) Greenhouse gases
D) Water
Answer: C
Greenhouse effect helps in:
A) Cooling Earth
B) Warming Earth
C) Drying soil
D) Freezing water
Answer: B
Which gas contributes most to greenhouse effect?
A) Oxygen
B) Carbon dioxide
C) Nitrogen
D) Hydrogen
Answer: B
Ozone layer protects from:
A) Infrared rays
B) Visible light
C) UV radiation
D) Gamma rays
Answer: C
Acid rain is caused by:
A) CO₂
B) SO₂ and NO₂
C) O₂
D) N₂
Answer: B
Ecosystem resilience means:
A) Weakness
B) Recovery ability
C) Growth
D) Decline
Answer: B
Which organism recycles nutrients fastest?
A) Plants
B) Animals
C) Microorganisms
D) Birds
Answer: C
Biotic potential refers to:
A) Maximum reproduction rate
B) Minimum reproduction
C) Survival rate
D) Death rate
Answer: A
Limiting factors include:
A) Food
B) Water
C) Space
D) All of these
Answer: D
Competition occurs when:
A) Resources are abundant
B) Resources are limited
C) No organisms present
D) Climate is stable
Answer: B
Predation is interaction between:
A) Two producers
B) Predator and prey
C) Two herbivores
D) Two decomposers
Answer: B
Symbiosis includes:
A) Mutualism
B) Parasitism
C) Commensalism
D) All of these
Answer: D
Mutualism benefits:
A) One organism
B) Both organisms
C) None
D) Only plants
Answer: B
Parasitism benefits:
A) Host
B) Parasite
C) Both
D) None
Answer: B
Commensalism benefits:
A) Both
B) One, other unaffected
C) None
D) Host only
Answer: B
Invasive species cause:
A) Biodiversity increase
B) Ecosystem imbalance
C) Stability
D) Growth
Answer: B
Which ecosystem has seasonal rainfall?
A) Desert
B) Tropical rainforest
C) Savanna
D) Tundra
Answer: C
Tundra ecosystem is characterized by:
A) High temperature
B) Permafrost
C) Heavy rainfall
D) Dense forest
Answer: B
Wetlands are important for:
A) Pollution
B) Water purification
C) Deforestation
D) Soil erosion
Answer: B
Coral reefs are:
A) Freshwater
B) Marine ecosystems
C) Desert ecosystems
D) Forest ecosystems
Answer: B
Which ecosystem is most productive per unit area?
A) Desert
B) Open ocean
C) Coral reefs
D) Tundra
Answer: C
100. Sustainable development means:
A) Using resources endlessly
B) Using resources wisely
C) Destroying ecosystems
D) Ignoring environment
Answer: B