Water hyacinth, the floating weed that chokes nutrient-rich water bodies, is popularly known as:
- A.Terror of Bengal
- B.Queen of the marshes
- C.Pride of the Deccan
- D.Golden weed
Correct answer
Explanation
The correct answer is A, terror of Bengal. Water hyacinth is an aquatic weed introduced into India from South America. In water enriched with sewage and fertiliser it grows so fast that it covers the surface, blocks sunlight, cuts the oxygen supply, clogs waterways and provides breeding grounds for mosquitoes; because it spread so violently in the water bodies of Bengal it earned the name terror of Bengal. Options B, C and D are wrong because none of them is a recognised name for this or any other aquatic weed; they are invented distractors placed there to see whether the standard phrase has been learnt. The weed is a textbook illustration of two ideas at once: the effect of eutrophication, and the damage an invasive alien species can do to a native ecosystem.
Read the full article: Water Pollution and River Cleaning: Causes and Schemes
Practice Questions
View allWhich pollution causes Itai-Itai disease in human beings?
- A.Mercury pollution
- B.Cadmium pollution
- C.Arsenic pollution
- D.Nitrate pollution
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Itai-Itai disease was first identified in Japan among people who ate rice grown with water polluted by cadmium from mining waste.
Read the full explanation →Minamata disease is caused by the pollution of water with which metal?
- A.Lead
- B.Mercury
- C.Cadmium
- D.Chromium
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Minamata disease takes its name from Minamata Bay in Japan, where a factory discharged mercury compounds that were converted by bacteria into methylmercury, concentrated in fish through biomagnification and then eaten by people.
Read the full explanation →A high value of biochemical oxygen demand in a water sample indicates:
- A.The water is clean and fit to drink
- B.Heavy load of organic pollution
- C.High dissolved oxygen
- D.Absence of bacteria
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Biochemical oxygen demand measures the oxygen that micro-organisms need in order to break down the organic matter present in a sample.
Read the full explanation →Blue baby syndrome, or methaemoglobinemia, in infants is caused by an excess of which substance in drinking water?
- A.Fluoride
- B.Nitrate
- C.Iron
- D.Calcium
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Nitrate from fertiliser run-off and from sewage seeps into groundwater; in an infant it is converted to nitrite, which binds to haemoglobin and forms methaemoglobin, a compound that cannot carry oxygen.
Read the full explanation →The excessive growth of algae in a water body due to enrichment with nitrates and phosphates is called:
- A.Biomagnification
- B.Eutrophication
- C.Salinisation
- D.Sedimentation
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When fertilisers, detergents and sewage add nitrates and phosphates to a lake or a slow-moving river, algae multiply into a bloom that covers the surface.
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