Ecology and Environment MCQs 2026

The maximum population size that an environment can sustain indefinitely is called

1. A Biotic potential ✓
2. B Carrying capacity ✓
3. C Population density ✓
4. D Growth rate ✓

Which of the following is an abiotic component of an ecosystem

1. A Bacteria ✓
2. B Fungi ✓
3. C Sunlight ✓
4. D Algae ✓

The transfer of energy from one trophic level to the next is best described by which ecological law

1. A Hardy-Weinberg law ✓
2. B Law of superposition ✓
3. C Mendel's law ✓
4. D Ten percent law (Lindeman's law) ✓

In a food chain, organisms that manufacture their own food using sunlight are called

1. A Producers ✓
2. B Primary consumers ✓
3. C Decomposers ✓
4. D Secondary consumers ✓

The sequential and predictable change in species composition of a community over time is called

1. A Ecological succession ✓
2. B Ecological pyramid ✓
3. C Biomagnification ✓
4. D Genetic drift ✓

Lichens are typically the pioneer species in which type of ecological succession

1. A Secondary succession ✓
2. B Primary succession on bare rock ✓
3. C Aquatic succession ✓
4. D Succession after fire ✓

A J-shaped population growth curve occurs when

1. A Resources are limited ✓
2. B Population reaches equilibrium ✓
3. C Growth is exponential with unlimited resources ✓
4. D Death rate exceeds birth rate ✓

The symbiotic relationship in which one organism benefits and the other is unaffected is called

1. A Mutualism ✓
2. B Parasitism ✓
3. C Predation ✓
4. D Commensalism ✓

Which gas is primarily responsible for the depletion of the ozone layer

1. A Carbon dioxide ✓
2. B Methane ✓
3. C Chlorofluorocarbons (CFCs) ✓
4. D Nitrogen ✓

The layer of the atmosphere where the ozone layer is located is the

1. A Troposphere ✓
2. B Mesosphere ✓
3. C Stratosphere ✓
4. D Thermosphere ✓

The phenomenon in which harmful substances like DDT increase in concentration at higher trophic levels is called

1. A Eutrophication ✓
2. B Succession ✓
3. C Competitive exclusion ✓
4. D Biomagnification ✓

Excessive nutrient enrichment of a water body leading to algal blooms and oxygen depletion is called

1. A Acid rain ✓
2. B Eutrophication ✓
3. C Bioaccumulation ✓
4. D Desertification ✓

Which of the following best describes a keystone species

1. A The most abundant species in an ecosystem ✓
2. B A species with no ecological role ✓
3. C A species whose impact on its ecosystem is disproportionately large relative to its abundance ✓
4. D A species found only in one location ✓

Rain with a pH lower than normal due to sulfur and nitrogen oxides is known as

1. A Acid rain ✓
2. B Alkaline rain ✓
3. C Photochemical smog ✓
4. D Greenhouse rain ✓

The main greenhouse gas contributing most to global warming is

1. A Oxygen ✓
2. B Nitrogen ✓
3. C Carbon dioxide ✓
4. D Argon ✓

The international agreement primarily aimed at phasing out substances that deplete the ozone layer is the

1. A Kyoto Protocol ✓
2. B Paris Agreement ✓
3. C Ramsar Convention ✓
4. D Montreal Protocol ✓

Species that are found nowhere else in the world except one particular region are called

1. A Invasive species ✓
2. B Keystone species ✓
3. C Indicator species ✓
4. D Endemic species ✓

Snow leopard and markhor are examples of endangered species found primarily in which part of Pakistan

1. A Coastal Sindh ✓
2. B Punjab plains ✓
3. C Thar Desert ✓
4. D Northern mountain regions ✓

Wetlands of international importance are designated under which convention

1. A Ramsar Convention ✓
2. B Montreal Protocol ✓
3. C Kyoto Protocol ✓
4. D Basel Convention ✓

The Indus River Dolphin is an example of a species conserved through

1. A Ex-situ conservation only ✓
2. B Zoo breeding programs only ✓
3. C In-situ conservation in its natural habitat ✓
4. D Seed bank preservation ✓

Ex-situ conservation of plant species is best exemplified by

1. A National parks ✓
2. B Wildlife sanctuaries ✓
3. C Seed banks and botanical gardens ✓
4. D Biosphere reserves ✓

The IUCN Red List category for a species facing an extremely high risk of extinction in the wild is

1. A Least Concern ✓
2. B Near Threatened ✓
3. C Vulnerable ✓
4. D Critically Endangered ✓

An ecological pyramid that is always upright and never inverted is the

1. A Pyramid of energy ✓
2. B Pyramid of numbers ✓
3. C Pyramid of biomass ✓
4. D Pyramid of productivity ✓

In a food web, organisms that feed on both plants and animals are called

1. A Herbivores ✓
2. B Omnivores ✓
3. C Carnivores ✓
4. D Decomposers ✓

Organisms that break down dead organic matter and recycle nutrients back into the ecosystem are called

1. A Producers ✓
2. B Consumers ✓
3. C Decomposers ✓
4. D Predators ✓

The functional role and position of a species within its ecosystem, including its interactions, is called its

1. A Ecological niche ✓
2. B Habitat ✓
3. C Biome ✓
4. D Community ✓

A biome characterized by extremely low temperatures, permafrost, and low biodiversity is the

1. A Tropical rainforest ✓
2. B Savanna ✓
3. C Temperate grassland ✓
4. D Tundra ✓

The largest reservoir of carbon on Earth in the carbon cycle is

1. A Atmosphere ✓
2. B Sedimentary rocks and fossil fuels ✓
3. C Living organisms ✓
4. D Freshwater bodies ✓

Nitrogen fixation, the conversion of atmospheric nitrogen into usable forms, is primarily carried out by

1. A Green plants directly ✓
2. B Fungi only ✓
3. C Herbivorous animals ✓
4. D Nitrogen-fixing bacteria such as Rhizobium ✓

The relationship between two species in which one benefits and the other is harmed is called

1. A Mutualism ✓
2. B Parasitism ✓
3. C Commensalism ✓
4. D Neutralism ✓

Coral reefs and clownfish anemones are classic examples of which ecological interaction

1. A Mutualism ✓
2. B Parasitism ✓
3. C Predation ✓
4. D Competition ✓

The total variety of life forms including genetic, species, and ecosystem diversity is called

1. A Population density ✓
2. B Ecological succession ✓
3. C Biodiversity ✓
4. D Trophic structure ✓

Regions with exceptionally high levels of endemic species facing significant habitat loss are called

1. A Biodiversity hotspots ✓
2. B Biosphere reserves ✓
3. C Ramsar sites ✓
4. D National parks ✓

Deforestation contributes to climate change primarily by

1. A Increasing oxygen levels ✓
2. B Reducing carbon dioxide absorption by trees ✓
3. C Increasing rainfall ✓
4. D Cooling the atmosphere ✓

The gradual reduction of usable land due to climatic changes and human activities, turning it into desert, is called

1. A Desertification ✓
2. B Eutrophication ✓
3. C Bioremediation ✓
4. D Afforestation ✓

Non-renewable natural resources include all of the following EXCEPT

1. A Coal ✓
2. B Solar energy ✓
3. C Petroleum ✓
4. D Natural gas ✓

The total impact of human activities measured in terms of biologically productive land and water required to support them is called

1. A Ecological footprint ✓
2. B Biomass index ✓
3. C Trophic efficiency ✓
4. D Carrying index ✓

Development that meets present needs without compromising the ability of future generations to meet their own needs is called

1. A Green revolution ✓
2. B Bioremediation ✓
3. C Sustainable development ✓
4. D Industrialization ✓

Which type of ecological succession begins in an area that previously supported life but was disturbed, such as after a fire or flood

1. A Primary succession ✓
2. B Secondary succession ✓
3. C Cyclic succession ✓
4. D Allogenic succession ✓

The climax community in ecological succession is characterized by

1. A Rapid species turnover ✓
2. B Dominance of pioneer species ✓
3. C High instability ✓
4. D A stable, self-perpetuating community in equilibrium with the environment ✓

Two species competing for the same limited resource in the same habitat, potentially leading to exclusion of one, illustrates

1. A Mutualism ✓
2. B Competition (competitive exclusion principle) ✓
3. C Commensalism ✓
4. D Parasitism ✓

The Kyoto Protocol primarily aims to

1. A Protect wetlands ✓
2. B Reduce greenhouse gas emissions ✓
3. C Ban ozone-depleting substances ✓
4. D Regulate hazardous waste trade ✓

Which agency is primarily responsible for environmental protection and regulation in Pakistan

1. A WAPDA ✓
2. B PMD ✓
3. C SUPARCO ✓
4. D Pakistan Environmental Protection Agency (Pak-EPA) ✓

A community of interacting organisms together with their physical environment is called

1. A Population ✓
2. B Ecosystem ✓
3. C Biome ✓
4. D Niche ✓

The Paris Agreement of 2015 primarily aims to

1. A Preserve wetlands ✓
2. B Regulate hazardous waste ✓
3. C Ban CFCs ✓
4. D Limit global temperature rise well below 2 degrees Celsius ✓

Bioaccumulation refers to

1. A Loss of biodiversity over time ✓
2. B Decomposition of organic waste ✓
3. C Gradual buildup of toxic substances within an individual organism over its lifetime ✓
4. D Nutrient cycling in soil ✓

Which type of pollution is caused primarily by excessive and unwanted sound levels harming human health

1. A Noise pollution ✓
2. B Thermal pollution ✓
3. C Radioactive pollution ✓
4. D Light pollution ✓

A pyramid of biomass in most terrestrial ecosystems is typically

1. A Upright, decreasing at higher trophic levels ✓
2. B Always inverted ✓
3. C Rectangular ✓
4. D Absent in terrestrial ecosystems ✓

The scientific study of interactions between organisms and their environment is called

1. A Physiology ✓
2. B Ecology ✓
3. C Taxonomy ✓
4. D Genetics ✓

Ecosystem services such as pollination, water purification, and climate regulation are examples of

1. A Benefits provided by nature to humans through ecological processes ✓
2. B Only economic goods ✓
3. C Man-made systems ✓
4. D Genetic resources only ✓