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Environmental Sciences Past Paper MCQs
Environmental Sciences 2024 MCQs
1 / 20
An association has been found between exposure to ______ by the inhalation route and lung cancer.
Chromium (Cr), especially hexavalent chromium (Cr-VI), is a known carcinogen linked to lung cancer when inhaled (e.g., in industrial settings).
2 / 20
The set of ecosystems is called:
A biome is a large community of plants and animals adapted to a specific environment (e.g., tropical rainforest, desert, tundra). It consists of multiple ecosystems with similar climatic conditions.
3 / 20
The result of acid deposition is:
Acid deposition (acid rain) lowers the pH of soil and water bodies, harming aquatic life, damaging forests, and corroding buildings.
4 / 20
An individual may die within 2 - 10 days after exposure to 500 ppm of the following air pollutant:
Sulfur dioxide (SO₂) at 500 ppm is highly toxic, causing respiratory failure and death within days due to severe lung irritation.
5 / 20
______ often serve as indicator for a threatened ecosystem.
Endangered species signal ecosystem stress, as their decline reflects habitat destruction, pollution, or climate change impacts.
6 / 20
Of the following agents, the one that would not favor conversion of sulfur dioxide to sulfate species in the atmosphere is:
Sunlight alone does not convert SO₂ to sulfates. Ammonia (NH₃) and water (H₂O) facilitate this reaction, forming sulfate aerosols.
7 / 20
A mutual relationship between two organisms, where both of them are benefiting from watching the other is called:
Mutualism is a symbiotic relationship where both species benefit (e.g., bees pollinating flowers while collecting nectar).
8 / 20
What percentage of oxygen and carbon dioxide exists in the ecosystem?
The Earth's atmosphere consists of approximately 20.95% oxygen (O₂) and 0.04% carbon dioxide (CO₂). These levels are critical for sustaining life and maintaining ecological balance.
9 / 20
Mangrove forests in Asia are largely concentrated in:
Indonesia has the largest mangrove coverage in Asia (about 23% of the world’s mangroves), vital for coastal protection and biodiversity.
10 / 20
Pakistan is divided into ______ agro - ecological zones.
Pakistan has 12 agro-ecological zones, classified based on climate, soil, and water availability for agricultural planning.
11 / 20
The greenhouse effect in the atmosphere is produced due to:
The greenhouse effect occurs when greenhouse gases (e.g., CO₂, CH₄) absorb infrared radiation (heat) emitted by the Earth's surface and re-radiate it, warming the planet.
12 / 20
The "Ramsar Convention" is an international treaty for the conservation and protection of:
The Ramsar Convention (1971) focuses on the conservation and sustainable use of wetlands of international importance.
13 / 20
NEQ was approved on:
The National Environmental Quality Standards (NEQS) in Pakistan were approved in 1995 to regulate industrial emissions and effluents.
14 / 20
Biotic component of the environment does not include:
Biotic components are living organisms (plants, animals, microbes). Soil is an abiotic (non-living) component, though it supports biotic life.
15 / 20
What is the order of waste management hierarchy, from most to least favoured?
The waste hierarchy prioritizes Prevention > Reuse > Recycle > Disposal to minimize environmental impact.
16 / 20
The pH of the atmosphere is:
The natural pH of rainwater is slightly acidic (~5.6) due to dissolved CO₂ forming carbonic acid. Pollution (SO₂, NOₓ) further lowers pH, causing acid rain.
17 / 20
Acid rain is a result of:
Acid rain is caused by the release of sulfur dioxide (SO₂) and nitrogen oxides (NOₓ) into the atmosphere, primarily from burning fossil fuels. These gases react with water vapor to form sulfuric and nitric acids.
18 / 20
Which gas produced in open dumps from the anaerobic decomposition of biodegradable waste?
Methane (CH₄) is a potent greenhouse gas generated by anaerobic decomposition in landfills and dumps.
19 / 20
______ is the increasing concentration of toxic substances in organisms as trophic levels increase in a food chain or food web.
Biomagnification refers to the accumulation of toxins (e.g., mercury, DDT) in higher trophic levels (e.g., predators like eagles).
20 / 20
A wide variety of living organisms is called:
Biodiversity refers to the variety of life on Earth, including species diversity, genetic diversity, and ecosystem diversity. It encompasses all living organisms, from microorganisms to plants and animals.
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