NEET Biology Environmental Issues MCQs Set 21

Answer: (d) Both

Explanation:
1. Scrubbers remove gases such as sulphur dioxide, and electrostatic precipitators remove particulate matter from exhausts.
2. Effluent treatment is for water, so the best choice is Both (scrubbers and precipitator) as the air devices.

Teacher's Note:
1. ESP can remove over 99 percent of particles.
2. Scrubbers use water or a chemical spray.

Answer: (b) O3

Explanation:
1. Ozone in the troposphere is harmful (a chemical weed) but in the stratosphere it absorbs UV rays and protects life.
2. CFCs and methane are harmful everywhere.

Teacher's Note:
1. Good ozone is in the stratosphere and bad ozone is near the ground.
2. Photochemical smog contains tropospheric ozone.

Answer: (c) Increased algal growth

Explanation:
1. Phosphates and nitrates in fertilisers and sewage enrich the water with nutrients, called eutrophication.
2. This increases algal growth, which later uses up oxygen.

Teacher's Note:
1. Eutrophication is natural ageing of lakes accelerated by human activity.
2. Algal blooms kill fish by oxygen depletion.

Answer: (b) BOD and turbidity

Explanation:
1. BOD (biochemical oxygen demand) shows the organic load, and turbidity shows suspended matter.
2. Together they are the better indicators of water pollution.

Teacher's Note:
1. High BOD means a more polluted water body.
2. Pure water has low BOD.

Answer: (a) Clogging of gills

Explanation:
1. An oil slick spreads over the water and coats the gills of fish, so they cannot breathe and die in large numbers.

Teacher's Note:
1. Oil also reduces oxygen entry into water.
2. Sea birds are also hit when oil sticks to feathers.

Answer: (b) Diffuse water pollution

Explanation:
1. Pesticide spray spreads over a wide area and reaches water by run-off.
2. Such pollution without a single entry point is diffuse (non-point) source pollution.

Teacher's Note:
1. Point source means a single pipe.
2. Run-off from farms is the usual non-point source.

Answer: (a) Incineration

Explanation:
1. Incineration is the burning of waste in the presence of oxygen at high temperature.
2. Pyrolysis is heating in the absence of oxygen.

Teacher's Note:
1. Incineration reduces waste volume.
2. It is used for hospital waste.

Answer: (d) Good fungal growth in soil

Explanation:
1. Global warming causes extreme weather, sea level rise and poleward shift of species.
2. Good fungal growth in soil is not an effect of global warming.

Teacher's Note:
1. Warming melts ice and expands sea water.
2. Species move to cooler places.

Answer: (a) I.A.P. – Indian Atmospheric Pollution

Explanation:
1. IAP stands for Index of Air Pollution, not Indian Atmospheric Pollution.
2. UNEP, CCC and ODP are expanded correctly.

Teacher's Note:
1. Learn common environmental abbreviations.
2. ODP measures ozone depleting potential.

Answer: (d) iii iv i ii

Explanation:
1. Eutrophication means nutrient enrichment.
2. A sanitary landfill is a waste disposal site.
3. Snow blindness comes from UV-B radiation.
4. Jhum cultivation is shifting cultivation causing deforestation.

Teacher's Note:
1. Match the term with the correct cause or effect.
2. Jhum is also called slash and burn.

Answer: (c) O3

Explanation:
1. Secondary pollutants are formed in the atmosphere from primary pollutants.
2. Ozone (O3) forms from the reaction of nitrogen oxides and hydrocarbons in sunlight.
3. CO, CO2 and SO2 are released directly.

Teacher's Note:
1. Examples of secondary pollutants are ozone, PAN and smog.
2. Primary pollutants are directly emitted.

Answer: (c) Water is highly polluted

Explanation:
1. BOD is the oxygen needed by microbes to break down organic matter in water.
2. A high BOD means a lot of organic matter, so the water is highly polluted.

Teacher's Note:
1. Low BOD means clean water.
2. BOD is measured in mg of oxygen per litre.

Answer: (d) Reducing deforestation, cutting down use of fossil fuel

Explanation:
1. Global warming is reduced by protecting forests (which take up CO2) and by cutting down fossil fuel use.
2. Deforestation and heavy fuel use raise CO2.

Teacher's Note:
1. Afforestation helps absorb CO2.
2. Fossil fuels are the main source of CO2.

Answer: (d) CoP - 3

Explanation:
1. The Kyoto Protocol was adopted in 1997 at the third Conference of the Parties (CoP 3).
2. It sets targets to reduce greenhouse gas emissions.

Teacher's Note:
1. Kyoto means CoP 3.
2. It deals with greenhouse gases.

Answer: (a) Stratosphere

Explanation:
1. Good ozone is the ozone of the stratosphere that absorbs harmful UV radiation.
2. Tropospheric ozone is bad ozone.

Teacher's Note:
1. Stratospheric ozone is a shield.
2. It is thinned by CFCs.

Answer: (c) Fresh water lakes

Explanation:
1. Eutrophication is mostly seen in fresh water lakes and ponds with limited water exchange.
2. The open ocean is too large to be enriched in this way.

Teacher's Note:
1. Slow-moving lakes collect nutrients.
2. Eutrophic lakes look green.

Answer: (c) The increased microbial activity uses up dissolved oxygen

Explanation:
1. Sewage contains organic matter.
2. Microbes decompose it and use up the dissolved oxygen of river water, so fish die.

Teacher's Note:
1. Sewage raises BOD.
2. It does not make water drinkable.

Answer: (a) Above 80 dB

Explanation:
1. Sounds above about 80 dB are regarded as hazardous noise.
2. Long exposure can damage hearing and cause stress.

Teacher's Note:
1. The normal speech level is about 60 dB.
2. Noise is measured in decibels.

Answer: (b) Sewage and agricultural fertilizers

Explanation:
1. Phosphate pollution is caused by sewage and agricultural fertilisers.
2. Detergents also add phosphates.

Teacher's Note:
1. Phosphates cause algal bloom.
2. Nitrates act in a similar way.

Answer: (c) Fishes

Explanation:
1. Biomagnification is the increase in the concentration of a toxic substance at successive trophic levels.
2. Among the options, fishes feed higher in the chain than planktons and kelps, so they show the maximum.

Teacher's Note:
1. Top predators carry the highest toxin load.
2. DDT is a classical example.

Answer: (c) Teeth

Explanation:
1. Excess fluoride in water causes dental and skeletal fluorosis.
2. Teeth are mainly affected, with mottling.

Teacher's Note:
1. Fluorosis comes from excess fluoride.
2. Safe limit is about 1 ppm.

Answer: (d) Phenyl

Explanation:
1. Chlorine, chloramine and ozone are used to disinfect drinking water.
2. Phenyl is a floor cleaner and is not used for drinking water.

Teacher's Note:
1. Disinfection kills germs.
2. Ozone leaves no taste.

Answer: (c) Increasing amount of atmospheric carbondioxide

Explanation:
1. Rising carbon dioxide increases the greenhouse effect and global warming.
2. Climate is therefore threatened by the increase in atmospheric CO2.

Teacher's Note:
1. CO2 is the main greenhouse gas.
2. Burning fossil fuels raises it.