Environment & Ecology MCQ Questions 2026 – Topic-wise Practice for UPSC, SSC, Forest Services

What is the term used for the process of converting sunlight into chemical energy by plants?

Respiration

Photosynthesis

Decomposition

Fermentation

Easy

💡 Explanation

Photosynthesis is the process by which plants, algae, and some bacteria convert light energy from the sun into chemical energy in the form of organic compounds, such as glucose.

Which of the following gases is a major contributor to the greenhouse effect?

Carbon dioxide

Methane

Nitrous oxide

All of the above

Medium

💡 Explanation

All three gases, carbon dioxide, methane, and nitrous oxide, are potent greenhouse gases that contribute to global warming and climate change.

What is the term used for the process of water cycling through the environment?

Water cycle

Hydrologic cycle

Evaporation

Condensation

Easy

💡 Explanation

The hydrologic cycle, also known as the water cycle, is the continuous process by which water is circulated between the Earth's oceans, atmosphere, and land surfaces.

Which of the following species is an endangered species in India?

Bengal tiger

Asiatic lion

Indian rhinoceros

All of the above

Medium

💡 Explanation

The Bengal tiger, Asiatic lion, and Indian rhinoceros are all endangered species in India, with declining populations due to habitat loss and human-wildlife conflict.

What is the term used for the movement of organisms from one region to another?

Migration

Dispersal

Invasion

Colonization

Easy

💡 Explanation

Migration refers to the seasonal or permanent movement of organisms from one region to another, often in search of food, water, or suitable habitats.

Which of the following types of ecosystems is characterized by a diverse array of plant and animal species?

Tropical rainforest

Desert ecosystem

Grassland ecosystem

Temperate deciduous forest

Medium

💡 Explanation

Tropical rainforests are among the most biodiverse ecosystems on the planet, with a vast array of plant and animal species, including many that are found nowhere else on Earth.

What is the term used for the amount of living matter in a given area?

Biodiversity

Species richness

Species evenness

Biological productivity

Easy

💡 Explanation

Species richness refers to the number of different species present in a given area, which is a key component of biodiversity.

Which of the following pollutants is a major contributor to acid rain?

Sulfur dioxide

Nitrogen oxides

Carbon monoxide

Particulate matter

Medium

💡 Explanation

Sulfur dioxide and nitrogen oxides are the primary pollutants responsible for acid rain, which can have devastating effects on ecosystems and human health.

What is the term used for the process of soil erosion caused by wind?

Water erosion

Wind erosion

Soil creep

Soil liquefaction

Easy

💡 Explanation

Wind erosion refers to the process of soil being blown away by wind, which can lead to soil loss and degradation of ecosystems.

Which of the following types of waste is a major contributor to pollution in India?

Industrial waste

Domestic waste

Agricultural waste

All of the above

Medium

💡 Explanation

Industrial waste, domestic waste, and agricultural waste all contribute to pollution in India, with significant impacts on human health and the environment.

What is the term used for the process of plants releasing water vapor into the atmosphere?

Transpiration

Evaporation

Condensation

Precipitation

Easy

💡 Explanation

Transpiration refers to the process by which plants release water vapor into the atmosphere, which is an important component of the water cycle.

Which of the following species is an example of a keystone species in a given ecosystem?

Lion

Elephant

Giraffe

Tiger

Medium

💡 Explanation

Lions are often considered keystone species in their ecosystems, playing a crucial role in maintaining the balance of their environments.

What is the term used for the movement of water from the land to the atmosphere?

Runoff

Infiltration

Evaporation

Transpiration

Easy

💡 Explanation

Evaporation refers to the process by which water moves from the land to the atmosphere, often in the form of water vapor.

Which of the following types of pollution is caused by the release of chemicals into the environment?

Air pollution

Water pollution

Soil pollution

Chemical pollution

Medium

💡 Explanation

Chemical pollution refers to the release of chemicals into the environment, which can have devastating effects on ecosystems and human health.

What is the term used for the process of soil formation through the weathering of rocks?

Soil creep

Soil erosion

Soil formation

Soil liquefaction

Easy

💡 Explanation

Soil formation refers to the process by which soil is created through the weathering of rocks, often over thousands of years.

Which of the following species is an example of a migratory species in India?

Bengal tiger

Asiatic lion

Indian rhinoceros

Bar-headed goose

Medium

💡 Explanation

The bar-headed goose is a migratory species in India, with populations that migrate between summer and winter habitats in the Himalayas.

What is the term used for the amount of waste generated by a given population?

Waste generation

Waste management

Waste disposal

Waste reduction

Easy

💡 Explanation

Waste generation refers to the amount of waste produced by a given population, which can have significant impacts on the environment.

Which of the following types of waste is a major contributor to pollution in urban areas?

Industrial waste

Domestic waste

Agricultural waste

Construction waste

Medium

💡 Explanation

Domestic waste is a major contributor to pollution in urban areas, with significant impacts on human health and the environment.

What is the term used for the process of water being stored in underground aquifers?

Groundwater recharge

Groundwater discharge

Surface water runoff

Evaporation

Easy

💡 Explanation

Groundwater recharge refers to the process by which water is stored in underground aquifers, often through infiltration of precipitation or surface water.

Which of the following species is an example of a threatened species in India?

Bengal tiger

Asiatic lion

Indian rhinoceros

All of the above

Medium

💡 Explanation

The Bengal tiger, Asiatic lion, and Indian rhinoceros are all threatened species in India, with declining populations due to habitat loss and human-wildlife conflict.