Insights Static Quiz -66, 2018 –Environment

Answer – b

• More than 70 per cent of all the species recorded are animals, while plants (including algae, fungi, bryophytes, gymnosperms and angiosperms) comprise no more than 22 per cent of the total.
• Among animals, insects are the most species-rich taxonomic group, making up more than 70 per cent of the total.
• The number of fungi species in the world is more than the combined total of the species of fishes, amphibians, reptiles and mammals.
• It should be noted that these estimates do not give any figures for prokaryotes. Biologists are not sure about how many prokaryotic species there might be. The problem is that conventional taxonomic methods are not suitable for identifying microbial species and many species are simply not culturable under laboratory conditions

Answer – c

• German naturalist and geographer Alexander von Humboldt observed that within a region species richness increased with increasing explored area, but only up to a limit.
• On a logarithmic scale, the relationship is a straight line described by the equation log S = log C + Z log A where
  S= Species richness, A= Area, Z = slope of the line (regression coefficient)
  C = Y-intercept

• Ecologists have discovered that the value of Z lies in the range of 0.1 to 0.2, regardless of the taxonomic group or the region (whether it is the plants in Britain,
  birds in California or molluscs in New York state, the slopes of the regression line are amazingly similar).
• But the species-area relationships among very large areas like the entire continents, the slope of the line to be much steeper (Z values in the range of 0.6 to 1.2).

Don’t be overawed by graph and formulas, it was justified to use them for better understanding only.

Answer – a

• Catalytic converters, having expensive metals namely platinum-palladium and rhodium as the catalysts, are fitted into automobiles for reducing emission of poisonous gases.
• As the exhaust passes through the catalytic converter, unburnt hydrocarbons are converted into carbon dioxide and water, and carbon monoxide and nitric oxide are changed to carbon dioxide and nitrogen gas, respectively.
• Motor vehicles equipped with catalytic converter should use unleaded petrol because lead in the petrol inactivates the catalyst

Answer – b

• Eutrophication is the natural aging of a lake by biological enrichment of its water. In a young lake the water is cold and clear, supporting little life.
• With time, streams draining into the lake introduce nutrients such as nitrogen and phosphorus, which encourage the growth of aquatic organisms. As the lake’s fertility increases, plant and animal life burgeons, and organic remains begin to be deposited on the lake bottom. Over the centuries, as silt and organic debris pile up, the lake grows shallower and warmer, with warm-water organisms supplanting those that thrive in a cold environment. Marsh plants take root in the shallows and begin to fill in the original lake basin.
• Eventually, the lake gives way to large masses of floating plants (bog), finally converting into land.

Answer – a