Free Forest Ecology MCQs with Answers

• A. SO2 and SO3
• B. SO2 and oxides of nitrogen
• C. Suspended particulate matter
• D. Hydrocarbons and N2O

Explanation: Suspended particulate matter scatters and absorbs light, producing haze and reducing visibility more directly than the listed gases.

• A. Tansley
• B. Odum
• C. Des Voeux
• D. Clements

Explanation: The word smog combines smoke and fog and was coined by Dr Henry Antoine des Voeux in 1905 while describing polluted London air.

• A. London
• B. Paris
• C. Tokyo
• D. New York

Explanation: Classical, or London-type, smog was characteristically observed in London under cool, humid conditions, with coal smoke and sulphur…

• A. Osteosclerosis
• B. Minamata disease
• C. Bright's disease
• D. Hashimoto disease

Explanation: Minamata disease is severe mercury poisoning caused by eating contaminated fish, especially from industrial methylmercury discharge.

• A. same as present
• B. Higher than the present
• C. Less than the present
• D. Dependent on the amount of O2 in the atmosphere

Explanation: Without atmospheric CO2, the greenhouse effect would be greatly weakened, so Earth's average surface temperature would be lower than it is…

• A. Suspended particles
• B. Thermal power plants
• C. Sewage
• D. Burning of fossil fuel

Explanation: In large cities, fossil-fuel combustion in vehicles, industries and heating systems is a major source of air pollution, releasing gases…

• A. Low
• B. High
• C. Same
• D. None of these

Explanation: Sewage contains abundant biodegradable organic matter, so microorganisms consume more oxygen while decomposing it and produce a high…

• A. Its cost of production is high
• B. Organisms at once developed resistance to it
• C. It is not rapidly degraded in nature
• D. It is significantly less effective than other pesticides

Explanation: DDT persists because microorganisms and natural processes break it down very slowly, allowing it to accumulate in soil, water and body…

• A. Increase in weed population
• B. Simplification of food web
• C. Reduction in population of useful birds
• D. The development of resistant pest varieties

Explanation: Repeated pesticide use selects the naturally resistant individuals, which survive and reproduce until the pest population becomes less…

• A. By forming a stable compound with haemoglobin
• B. By destroying the haemoglobin
• C. By changing O2 into CO
• D. By obstructing the reaction of O2 with haemoglobin

Explanation: Carbon monoxide binds haemoglobin to form carboxyhaemoglobin, a stable compound that prevents haemoglobin from carrying oxygen…

• A. It gives off a bad small
• B. It removes the food eaten by fishes
• C. It increases the competition with fishes for dissolved oxygen
• D. Excessive CO2 is added to water

Explanation: Organic sewage is decomposed by microorganisms that consume dissolved oxygen, increasing the biological oxygen demand of the water.

• A. Natural flora of a place
• B. Natural gaseous cycle
• C. Natural geochemical cycle
• D. Natural balance of our ecological environment

Explanation: Pollution first disturbs the ecological balance because organisms, food chains and natural interactions respond directly to contaminants.

• A. Fish contaminated with mercury
• B. Sea food containing lot of cadmium
• C. Oysters with lot of pesticide
• D. Sea food contaminated with selenium

Explanation: Minamata disease resulted from methylmercury discharged into water, which accumulated in aquatic organisms and biomagnified in fish and…

• A. Mosses
• B. Lichens
• C. Liver worts
• D. Ferns

Explanation: Lichens are especially sensitive to atmospheric sulphur dioxide, so their disappearance or reduced growth indicates SO2 pollution.

• A. Phytoplanktons
• B. Birds
• C. Zooplanktons
• D. Fishes

Explanation: Biomagnification increases at successive trophic levels, so predatory fishes contain much higher pollutant concentrations than plankton.

• A. 20 times
• B. 100 times
• C. 2 times
• D. 200 times

Explanation: Carbon monoxide has approximately 200 to 250 times greater affinity for haemoglobin than oxygen, enabling it to displace oxygen and form…

• A. Biogas generation
• B. Biological oxygen demand
• C. Biosynthetic path way
• D. Fermentation

Explanation: Biological oxygen demand is estimated from the oxygen consumed by microorganisms while decomposing organic matter in water over a…

• A. SO2 layer
• B. O3 layer
• C. O2 Layer
• D. CO2 layer

Explanation: Supersonic aircraft can release nitrogen oxides at high altitude, promoting ozone destruction in the stratosphere.

• A. Cooling of earth
• B. Trapping UV rays
• C. Production of cereals
• D. warming of earth

Explanation: Greenhouse gases absorb outgoing infrared radiation and re-radiate part of it back toward Earth, raising the planet's average temperature.

• A. Reacts with haemoglobin
• B. It inhibits glycolysis
• C. It reacts with O2
• D. Makes nervous system inactive

Explanation: Carbon monoxide binds strongly with haemoglobin to form carboxyhaemoglobin, reducing the blood's capacity to carry oxygen.