Q.1 What is the primary source of energy for most ecosystems?
Soil nutrients
Sunlight
Water
Wind
Explanation - Sunlight is the primary energy source for most ecosystems because it drives photosynthesis in plants, which forms the base of the food chain.
Correct answer is: Sunlight
Q.2 Which of the following best defines biodiversity?
Number of plants in an area
Variety of life forms in an ecosystem
Amount of rainfall in a region
Presence of a single species
Explanation - Biodiversity refers to the variety and variability of life in a particular habitat or ecosystem, including species, genetic, and ecosystem diversity.
Correct answer is: Variety of life forms in an ecosystem
Q.3 Which of these is an example of a keystone species?
Elephant
Lion
Beetle
Dandelion
Explanation - Keystone species have a disproportionate effect on their ecosystem. Elephants, for example, shape savanna ecosystems by modifying vegetation and creating habitats for other species.
Correct answer is: Elephant
Q.4 What type of interaction occurs when one species benefits and the other is unaffected?
Mutualism
Commensalism
Parasitism
Competition
Explanation - In commensalism, one species benefits while the other remains unaffected, such as barnacles on whales.
Correct answer is: Commensalism
Q.5 Which ecosystem has the highest biodiversity?
Desert
Tropical rainforest
Tundra
Grassland
Explanation - Tropical rainforests have the highest biodiversity due to favorable climate, abundant rainfall, and complex habitat structures.
Correct answer is: Tropical rainforest
Q.6 Which of the following is a biotic component of an ecosystem?
Temperature
Sunlight
Plants
Soil pH
Explanation - Biotic components are living organisms in an ecosystem, such as plants, animals, fungi, and bacteria.
Correct answer is: Plants
Q.7 The loss of which type of species can cause a trophic cascade?
Primary producer
Top predator
Decomposer
Invasive species
Explanation - Top predators regulate populations of species below them in the food chain. Their removal can lead to overpopulation of prey and ecosystem imbalance.
Correct answer is: Top predator
Q.8 Which term describes the variety of genes within a species?
Species diversity
Ecosystem diversity
Genetic diversity
Functional diversity
Explanation - Genetic diversity refers to the variation of genes within a species, which helps populations adapt to environmental changes.
Correct answer is: Genetic diversity
Q.9 What is the role of decomposers in an ecosystem?
Produce energy
Recycle nutrients
Consume top predators
Compete with plants
Explanation - Decomposers like fungi and bacteria break down dead organic matter, releasing nutrients back into the soil for plant growth.
Correct answer is: Recycle nutrients
Q.10 Which of the following is a threat to biodiversity?
Reforestation
Pollution
Habitat restoration
Ecotourism
Explanation - Pollution, habitat loss, overexploitation, invasive species, and climate change are major threats to biodiversity.
Correct answer is: Pollution
Q.11 What is an invasive species?
A species native to an area
A species that benefits the ecosystem
A species introduced to a new area causing harm
A species at the top of the food chain
Explanation - Invasive species are non-native organisms that disrupt ecosystems by outcompeting native species or altering habitats.
Correct answer is: A species introduced to a new area causing harm
Q.12 Which type of ecosystem provides the largest carbon sink?
Grasslands
Oceans
Tropical rainforests
Deserts
Explanation - Oceans absorb and store vast amounts of carbon dioxide, making them the largest carbon sink on Earth.
Correct answer is: Oceans
Q.13 Which of the following is a freshwater ecosystem?
Mangrove
Coral reef
River
Estuary
Explanation - Freshwater ecosystems include rivers, lakes, ponds, and wetlands, characterized by low salt content.
Correct answer is: River
Q.14 The term 'ecological niche' refers to:
The physical location of a species
The role a species plays in its ecosystem
The number of individuals in a species
The diet of a species
Explanation - An ecological niche describes how a species interacts with its environment, including its habitat, diet, and relationships with other species.
Correct answer is: The role a species plays in its ecosystem
Q.15 Which of these is an example of mutualism?
Tick on a dog
Bees pollinating flowers
Cactus in a desert
Barnacles on a whale
Explanation - Mutualism is an interaction where both species benefit, such as bees obtaining nectar while pollinating flowers.
Correct answer is: Bees pollinating flowers
Q.16 Which factor most influences the distribution of species on Earth?
Human population
Climate and habitat
Color of species
Number of predators
Explanation - Species distribution is primarily determined by climate, vegetation, water availability, and habitat conditions.
Correct answer is: Climate and habitat
Q.17 Eutrophication in water bodies is caused mainly by:
Oxygen increase
Nutrient enrichment
Temperature drop
Water flow increase
Explanation - Eutrophication occurs when excess nutrients, especially nitrogen and phosphorus, cause algae blooms, depleting oxygen and harming aquatic life.
Correct answer is: Nutrient enrichment
Q.18 Which biome is characterized by very low temperatures and permafrost?
Tropical rainforest
Desert
Tundra
Savanna
Explanation - The tundra biome has extremely cold climates, short growing seasons, and permafrost, with limited plant and animal life.
Correct answer is: Tundra
Q.19 Primary succession begins on:
Bare rock
Grassland
Forest soil
Mangrove swamps
Explanation - Primary succession occurs on lifeless areas with no soil, such as bare rock, where pioneer species like lichens initiate soil formation.
Correct answer is: Bare rock
Q.20 Which of the following is a major ecosystem service?
Banking
Pollination
Transportation
Mining
Explanation - Ecosystem services are benefits humans get from nature. Pollination by insects is crucial for crop production.
Correct answer is: Pollination
Q.21 Coral reefs are most threatened by:
Desertification
Ocean acidification
Overfishing
Both B and C
Explanation - Coral reefs are threatened by ocean acidification, rising temperatures, and human activities like overfishing and pollution.
Correct answer is: Both B and C
Q.22 Which of the following is an example of an abiotic factor?
Bacteria
Sunlight
Trees
Deer
Explanation - Abiotic factors are non-living components of ecosystems such as sunlight, temperature, water, and soil.
Correct answer is: Sunlight
Q.23 Which human activity is most responsible for habitat fragmentation?
Urbanization
Composting
Recycling
Organic farming
Explanation - Urbanization and infrastructure development divide habitats into smaller patches, disrupting species movement and survival.
Correct answer is: Urbanization
Q.24 Which of the following best represents ecosystem resilience?
Ability to resist change
Ability to recover after disturbance
Number of species
Amount of rainfall
Explanation - Ecosystem resilience is the capacity of an ecosystem to recover after disturbances such as fires, floods, or human activities.
Correct answer is: Ability to recover after disturbance
Q.25 Mangroves are important because they:
Prevent desertification
Act as natural coastal barriers
Increase industrial output
Decrease rainfall
Explanation - Mangroves protect coastlines from erosion, reduce storm surge impacts, and provide habitat for many species.
Correct answer is: Act as natural coastal barriers