Extensive growth of planktonic algae that imparts distinct colors to water bodies is called:
- Eutrophication
- Biomagnification
- Salinization
- Algal bloom
Explanation: Nutrient enrichment causes massive overgrowth of algae, termed an algal bloom, which drastically deteriorates water quality.
In agricultural areas, groundwater is most commonly polluted by the leaching of soluble:
- Industrial dyes
- Nitrates and phosphates
- Radioactive isotopes
- Heavy metals
Explanation: Chemical fertilizers are highly soluble in water and easily leach into groundwater aquifers, contaminating them with nitrates and phosphates.
The increase in concentration of a toxicant at successive trophic levels is called:
- Biofortification
- Biomagnification
- Eutrophication
- Bioremediation
Explanation: Biomagnification refers to the accumulation of non-biodegradable toxic substances (like DDT or mercury) at higher trophic levels in a food chain.
Excess fluoride in drinking water primarily causes crippling abnormalities in the:
- Heart and lungs
- Teeth and bones
- Liver and kidneys
- Nervous system
Explanation: Chronic ingestion of high fluoride levels leads to dental and skeletal fluorosis, which causes mottling of teeth and severe bone deformities.
Heated wastewater flowing out of electricity-generating units constitutes:
- Chemical pollution
- Organic pollution
- Radioactive pollution
- Thermal pollution
Explanation: Thermal wastewater eliminates organisms sensitive to high temperatures and drastically alters the local aquatic environment.
High concentration of fluoride in drinking water primarily causes defects in:
- Heart and lungs
- Brain and nerves
- Teeth and bones
- Liver and kidneys
Explanation: Excess fluoride causes skeletal and dental fluorosis, leading to mottled teeth and crippled bones.
The Arcata Marsh project purifies municipal wastewater by passing it through a series of marshes containing:
- Activated charcoal
- Algae and plants
- Chemical scrubbers
- Osmosis membranes
Explanation: The biological stage of the Arcata project uses marshes seeded with appropriate plants, algae, fungi, and bacteria to neutralize remaining pollutants.
A sudden influx of heated water from industries into a river drastically lowers the concentration of:
- Nitrogen gas
- Carbon dioxide
- Hydrogen sulfide
- Dissolved oxygen
Explanation: As the temperature of water increases due to thermal pollution, the solubility of gases, particularly essential dissolved oxygen, drops significantly.
Some bloom-forming algae are highly toxic to humans and can cause severe mortality in:
- Terrestrial mammals
- Fishes and livestock
- Avian populations
- Amphibian populations
Explanation: Toxic algal blooms (like red tides caused by dinoflagellates or certain cyanobacteria) release toxins that kill fishes, livestock, and can harm humans.
Which heavy metal is responsible for the painful bone disease known as Itai-itai?
- Mercury
- Lead
- Cadmium
- Arsenic
Explanation: Itai-itai disease was documented in Japan and was caused by mass cadmium poisoning, leading to extreme softening of bones and kidney failure.
Blackfoot disease is caused by chronic exposure to water contaminated with:
- Mercury
- Fluoride
- Cadmium
- Arsenic
Explanation: Blackfoot disease is a severe form of peripheral vascular disease resulting from chronic, long-term arsenic exposure.
For a pollutant to biomagnify, it must be non-biodegradable and highly soluble in:
Explanation: Toxicants that are fat-soluble (lipophilic) and non-biodegradable accumulate in tissues because they cannot be easily metabolized or excreted.
Methemoglobinemia, commonly known as Blue Baby Syndrome, is caused by excessive:
- Nitrates
- Sulfates
- Phosphates
- Chlorides
Explanation: High nitrate levels in drinking water reduce the oxygen-carrying capacity of an infant's blood, causing Blue Baby Syndrome.
In an aquatic ecosystem affected by DDT, the highest concentration is found in:
- Zooplankton
- Top carnivores
- Phytoplankton
- Small fishes
Explanation: Due to biomagnification, persistent toxins like DDT accumulate in fat tissues and reach their highest concentrations in top carnivores like fish-eating birds.
What percentage of impurities makes domestic sewage completely unfit for human use?
- One point zero
- Zero point one
- Ten point zero
- Five point zero
Explanation: According to NCERT, a mere 0.1 percent impurities (suspended solids, colloidal materials, dissolved materials) make domestic sewage unfit for human use.
The 'Friends of the Arcata Marsh' (FOAM) project successfully integrated artificial and:
- Natural processes
- Mechanical processes
- Chemical processes
- Nuclear processes
Explanation: The Arcata marsh project uses a mix of conventional filtering and natural biological processes (using plants, algae, bacteria) to treat wastewater.
The prime chemical contaminants responsible for driving cultural eutrophication are primarily:
- Heavy metal ions
- Sulfates and chlorides
- Carbonates and bicarbonates
- Nitrates and phosphates
Explanation: These two nutrients act as fertilizers for algae, triggering explosive algal blooms that characterize cultural eutrophication.
The accelerated aging of lakes largely due to human activities is properly called:
- Cultural eutrophication
- Biomagnification
- Natural eutrophication
- Biological magnification
Explanation: When human activities (like agricultural runoff and sewage) rapidly accelerate the nutrient enrichment and aging of a lake, it is called cultural or accelerated eutrophication.
Severe methylmercury poisoning from industrial wastewater in Japan historically caused:
- Blue baby syndrome
- Itai itai disease
- Minamata disease
- Blackfoot disease
Explanation: Minamata disease is a severe neurological syndrome caused by eating fish highly contaminated with methylmercury from industrial discharges.
EcoSan toilets are a sustainable and hygienic ecological sanitation method for handling:
- Industrial effluents
- Human excreta
- Radioactive waste
- Hospital waste
Explanation: EcoSan is a dry composting toilet system that recycles human excreta into natural fertilizer, reducing the need for chemical fertilizers.
Downstream from a sewage discharge point, as water becomes cleaner, the BOD level gradually:
- Fluctuates wildly
- Increases continuously
- Remains completely constant
- Drops significantly
Explanation: As microbes decompose the organic matter and the water naturally purifies downstream, the Biochemical Oxygen Demand (BOD) drops significantly.
Elements with a density greater than 5 g/cm³ are generally classified as:
- Noble metals
- Heavy metals
- Alkali metals
- Transition nonmetals
Explanation: Heavy metals like mercury, cadmium, copper, and lead have a relatively high density (greater than 5 g/cm³) and are highly toxic.
In an aquatic food chain, the highest concentration of DDT is usually found in:
- Fish eating birds
- Small fishes
- Large fishes
- Zooplankton
Explanation: Due to biomagnification, top carnivores like fish-eating birds accumulate the highest concentrations of persistent toxins like DDT.
The sudden disappearance of clean water organisms immediately downstream indicates a sharp spike in:
- Biological oxygen demand
- Dissolved oxygen
- Water transparency
- Photosynthetic rate
Explanation: A high BOD immediately downstream of a sewage pipe depletes dissolved oxygen, causing the death of sensitive clean water fish and flora.
Chronic exposure to cadmium-contaminated water is known to cause a painful bone disease called:
- Minamata disease
- Itai itai disease
- Blackfoot disease
- Dental fluorosis
Explanation: Itai-itai disease, recognized in Japan, was caused by cadmium poisoning which resulted in severe pain in the spine and joints, and softening of bones.
The release of heated wastewater into a river primarily reduces the concentration of:
- Dissolved carbon dioxide
- Toxic chemicals
- Dissolved oxygen
- Heavy metals
Explanation: As water temperature increases due to thermal pollution, the solubility of gases, including essential dissolved oxygen, decreases significantly.
The presence of which bacteria in water is a standard indicator of fecal pollution?
- Rhizobium
- Lactobacillus
- Streptococcus
- Coliform bacteria
Explanation: Coliform bacteria, typically found in the human intestine, serve as standard indicator organisms for fecal water pollution.
Extensive irrigation of crops without proper drainage primarily leads to which severe soil problem?
- Soil erosion
- Desertification
- Nutrient depletion
- Water logging
Explanation: Irrigation without adequate drainage of water leads to waterlogging in the soil, which affects the aeration of roots and damages crop yields.
The amount of naturally dissolved oxygen is usually highest in which type of water?
- Fast flowing stream
- Raw sewage
- Stagnant pond
- Polluted river
Explanation: Fast-flowing, turbulent streams constantly aerate the water, maximizing the concentration of dissolved oxygen.
Algal blooms impart a distinct color to water bodies and severely deteriorate the:
- Soil fertility
- Air quality
- Water quality
- Heavy metal content
Explanation: Algal blooms drastically deteriorate water quality and increase fish mortality due to severe oxygen depletion.
Chronic exposure to arsenic through contaminated groundwater can lead to a condition known as:
- Minamata disease
- Dental fluorosis
- Itai itai disease
- Blackfoot disease
Explanation: Long-term consumption of arsenic-contaminated water causes peripheral vascular disease, famously known as Blackfoot disease, characterized by gangrene.
Ecological sanitation (EcoSan) toilets offer a sustainable system for handling:
- Human excreta
- Industrial waste
- Hospital waste
- Radioactive waste
Explanation: EcoSan toilets use a dry composting method for managing human excreta efficiently, hygienically, and cost-effectively, converting it into natural fertilizer.
The presence of which specific organism in drinking water strongly indicates fecal contamination?
- Escherichia coli
- Pseudomonas putida
- Streptococcus lactis
- Bacillus subtilis
Explanation: E. coli is a coliform bacterium typically found in the human intestine. Its presence in water indicates contamination by human feces.
Heated effluents from power plants are generally harmful because they abruptly eliminate:
- Cold water organisms
- Heat tolerant microbes
- Pathogenic viruses
- Thermophilic bacteria
Explanation: Thermal pollution severely disrupts the local ecosystem by killing organisms adapted to colder temperatures and reducing dissolved oxygen.
The presence of large amounts of E. coli in water specifically indicates contamination by:
- Agricultural runoff
- Heavy metals
- Fecal matter
- Industrial effluents
Explanation: Escherichia coli is a coliform bacterium found in human intestines; its high presence in water strongly indicates recent fecal contamination.
Over centuries, natural eutrophication causes a lake to gradually become:
- Highly saline
- Deeper and colder
- Shallower and warmer
- Highly acidic
Explanation: As silt and organic debris pile up, the lake grows shallower and warmer, eventually transforming into land.
Planktonic algae multiply rapidly in water bodies primarily due to excessive amounts of:
- Dissolved oxygen
- Heavy metals
- Nutrients
- Thermal pollution
Explanation: Large amounts of nutrients, particularly nitrogen and phosphorus, stimulate the excessive growth of planktonic algae, causing algal blooms.
In the Arcata marsh project, the conventional first stage of water treatment strictly involves:
- Bacterial decomposition
- Sedimentation and filtering
- Algal nutrient absorption
- Heavy metal extraction
Explanation: The primary treatment is conventional, involving physical sedimentation, filtering, and chlorine treatment before the water enters the biological marshes.
Which parameter is used to estimate the amount of biodegradable organic matter in sewage?
- Dissolved Oxygen
- Total Suspended Solids
- Biochemical Oxygen Demand
- Chemical Oxygen Demand
Explanation: BOD is standardly used to measure the amount of oxygen microbes need to digest the biodegradable organic matter in water.
The coliform test is routinely performed on drinking water to detect potential contamination by:
- Heavy metals
- Chemical fertilizers
- Industrial solvents
- Human fecal matter
Explanation: Testing for coliform bacteria like E. coli is a standard method to determine if a water supply has been contaminated with sewage or human feces.
Water logging in agricultural fields draws soluble salts to the surface, causing severe:
- Biomagnification
- Eutrophication
- Acidification
- Salinization
Explanation: Waterlogging draws salts to the surface of the soil. The salt is deposited as a thin crust, causing salinization that is highly toxic to plant roots.
As the BOD of a water body increases, its dissolved oxygen (DO) level typically:
- Decreases rapidly
- Fluctuates randomly
- Remains constant
- Increases sharply
Explanation: High BOD means microorganisms are consuming large amounts of oxygen to break down organic waste, thereby depleting the dissolved oxygen.
Eutrophication is mainly driven by the excessive accumulation of nitrates and:
- Sulfates
- Carbonates
- Chlorides
- Phosphates
Explanation: Nitrates and phosphates act as prime plant nutrients that fuel the excessive growth of algae during cultural eutrophication.
The Ganga Action Plan (GAP) was launched by the Indian government in the year:
Explanation: The Ganga Action Plan was launched in 1985 to improve water quality through the interception, diversion, and treatment of domestic sewage.
Clean, unpolluted water typically has a Biochemical Oxygen Demand (BOD) value of less than:
- Five ppm
- Fifteen ppm
- Hundred ppm
- Fifty ppm
Explanation: Clean water has a very low BOD (usually less than 5 ppm), indicating minimal biodegradable organic matter is present.
Fish mortality increases significantly when the dissolved oxygen level falls below:
- Sixteen ppm
- Four ppm
- Twelve ppm
- Eight ppm
Explanation: Most aquatic life, particularly sensitive fish species, cannot survive when dissolved oxygen (DO) levels drop below 4 ppm.
High concentrations of DDT in birds primarily disrupt the metabolism of:
- Magnesium
- Calcium
- Potassium
- Sodium
Explanation: DDT disturbs calcium metabolism in birds, causing the thinning of eggshells and their premature breaking, leading to population decline.
Which genetically engineered bacterium is extensively utilized for clearing marine oil spills?
- Escherichia coli
- Agrobacterium tumefaciens
- Bacillus thuringiensis
- Pseudomonas putida
Explanation: The 'superbug' Pseudomonas putida was genetically engineered by Dr. A.M. Chakrabarty to degrade multiple components of crude oil.
Domestic sewage primarily consists of biodegradable organic matter, which is easily decomposed by:
- Viruses and prions
- Algae and plants
- Fungi and protozoa
- Bacteria and fungi
Explanation: Bacteria and other micro-organisms multiply rapidly using the organic substances present in sewage, driving natural decomposition.
High nitrate concentration in drinking water causes methemoglobinemia in infants, commonly called:
- Blackfoot disease
- Minamata disease
- Down syndrome
- Blue baby syndrome
Explanation: Nitrates bind to hemoglobin, reducing the blood's oxygen-carrying capacity and giving the infant's skin a bluish tint.
In a sewage treatment plant, the vital process of reducing BOD is accomplished by:
- Chemical precipitation
- Aerobic microbes
- Physical filtration
- Anaerobic microbes
Explanation: During secondary treatment, vigorous growth of aerobic microbes into 'flocs' consumes the major part of the organic matter, significantly reducing the BOD.
Accelerated eutrophication of lakes is primarily caused by effluents from:
- Nuclear reactors
- Industries and homes
- Plastic factories
- Thermal power plants
Explanation: Cultural or accelerated eutrophication is driven by human activities, especially nutrient-rich effluents from homes, agriculture, and industries.
Eichhornia crassipes, a highly invasive aquatic weed, is popularly known as the:
- Curse of Kerala
- Terror of Bengal
- Weed of Assam
- Sorrow of Bihar
Explanation: Water hyacinth is called the 'Terror of Bengal' because it grows abundantly in eutrophic water bodies, depleting oxygen and killing native fish.
The natural aging of a lake by biological enrichment of its water is known as:
- Eutrophication
- Stratification
- Biomagnification
- Siltation
Explanation: Natural eutrophication is the slow, natural aging of a lake over thousands of years due to nutrient enrichment from runoff.
The Water (Prevention and Control of Pollution) Cess Act was enacted in India in:
Explanation: To augment the resources of the Pollution Control Boards, the Water Cess Act was enacted in 1977.
A major health hazard associated with groundwater in parts of West Bengal is:
- Nitrate contamination
- Arsenic contamination
- Lead contamination
- Fluoride contamination
Explanation: Arsenic contamination of groundwater is a severe public health issue in the Bengal basin, leading to chronic arsenicosis.
The Water (Prevention and Control of Pollution) Act was passed in India in:
Explanation: The Government of India passed the Water Act in 1974 to safeguard water resources from industrial and domestic pollution.
Biochemical Oxygen Demand (BOD) is a measure of the polluting capacity of:
- Radioactive waste
- Industrial effluents
- Organic matter
- Heavy metals
Explanation: BOD measures the amount of oxygen required by bacteria to decompose biodegradable organic matter present in a water sample.
Minamata disease in Japan was caused by the consumption of fish contaminated with:
- Cadmium
- Mercury
- Arsenic
- Lead
Explanation: Minamata disease is a severe neurological syndrome caused by severe methylmercury poisoning from industrial wastewater.
Elements with a density greater than $5\text{ g/cm}^3$ that cause severe water toxicity are:
- Heavy metals
- Halogens
- Noble gases
- Alkaline earth metals
Explanation: Toxins like mercury, cadmium, copper, and lead are heavy metals, characterized by a density over $5\text{ g/cm}^3$.