The number of the correct statements regarding organic farming, amongst the following, are:
| I: | Organic farming encourages crop diversity and often employs polyculture. | 
| II: | Organic farming relies heavily on the natural breakdown of organic matter. | 
| III: | Organic weed management promotes weed elimination, rather than weed suppression | 
| IV: | Pest are used under Integrated Pest Management | 
| V: | Raising livestock and poultry, for meat, dairy and eggs, is another traditional farming activity that complements growing. | 
| VI: | It promotes use of genetically engineered plants and animals. | 
1. Three
2. Four
3. Five
4. Six
The accidental leakage of radioactive wastes occurred in the “Three Mile Island” and “Chernobyl” respectively in:
| 1. | 1979 and 1986 | 2. | 1981 and 1988 | 
| 3. | 1985 and 1991 | 4. | 1987 and 1999 | 
The environmental effects of global warming include all the following except:
| 1. | Arctic sea ice decline, sea level rise, retreat of glaciers | 
| 2. | Extreme weather, extreme events, tropical cyclones | 
| 3. | Ocean oxygenation and increased alkalinity of ocean waters | 
| 4. | Runaway and abrupt climate change | 
The common misconceptions regarding ozone depletion include:
| I. | Since CFC molecules are heavier than air (nitrogen or oxygen), the CFC molecules cannot reach the stratosphere in a significant amount. | 
| II. | Natural sources of tropospheric chlorine are four to five times larger than man-made ones and are responsible for ozone depletion. | 
| III. | The ozone hole should be above the sources of CFCs. | 
| 1. | Only I and II | 2. | Only I and III | 
| 3. | Only II and III | 4. | I, II, and III | 
Why is carbon dioxide regarded as a greenhouse gas?
| 1. | It is involved in photosynthesis | 
| 2. | It absorbs infrared radiation | 
| 3. | It emits visible radiation | 
| 4. | It absorbs and emits ultraviolet radiation | 
The levels of carbon dioxide is consistently increasing over the last 100+ years mainly because:
| 1. | increased respiration by increasing the human population. | 
| 2. | increased worldwide standing crop. | 
| 3. | an increase in the amount of infrared radiation absorbed by the atmosphere. | 
| 4. | the burning of larger amounts of wood and fossil fuels. | 
The thawing of permafrost in many areas of the tundra biome as a result of global warming is of concern mainly because:
| 1. | it will decrease the abundance and diversity of soil-dwelling organisms in tundra habitats. | 
| 2. | the bacterial decomposition of the thawed organic materials will produce large quantities of CO2, increasing global warming. | 
| 3. | Oil and coal deposits will rise to the surface | 
| 4. | migration of the human population will occur towards the tropics. | 
The highest concentration of polycarbonated biphenyls [PCBs] in a lake is expected in:
| 1. | Small fish | 2. | Sediment | 
| 3. | Phytoplankton | 4. | Zooplankton | 
The addition of fertilizers is frequently required in agricultural lands but not in wild mainly because:
| 1. | nitrogen-fixing bacteria and detrivores are less potent in agricultural lands. | 
| 2. | the nutrients that enter the plants are not returned to the soil on lands where they are harvested. | 
| 3. | the agricultural lands are selected for their oligotrophic soils. | 
| 4. | cultivation of agricultural lands inhibits the decomposition of organic matter. | 
What is most likely to occur due to continued global warming?
| 1. | Poleward movement of plant communities | 
| 2. | A fall in the sea levels | 
| 3. | Increased decomposition of organic matter in the polar region | 
| 4. | Increase in tundra regions |