2nd PUC Biology Question Bank Chapter 16 Environmental Issues

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Karnataka 2nd PUC Biology Question Bank Chapter 16 Environmental Issues

2nd PUC Biology Environmental Issues One Mark Questions and Answers

Question 1.
Define pollution.
Answer:
It is the undesirable change in physical, chemical and biological characteristics of our environment, adversely affecting human health and life of domestic animals.

Question 2.
What are pollutants?
Answer:
The pollution causing factors are called pollutants.

Question 3.
What are biodegradable pollutants?
Answer:
These pollutants that can be degraded into harmless products by decomposers like bacteria and fungi.

Question 4.
Give an example of a non-biodegradable pollutant.
Answer:
DDT.

Question 5.
What are CFCs?
Answer:
Chloro Fluoro Carbons.

Question 6.
What are PCBs?
Answer:
Poly Chlorinated Biphenyls.

Question 7.
What is CNG?
Answer:
Compressed Natural Gas.

Question 8.
What type of pollution is controlled by use of CNG?
Answer:
Air pollution.

Question 9.
What is ESP?
Answer:
Electrostatic Precipitators.

Question 10.
What is BOD?
Answer:
Biochemical Oxygen Demand.

Question 11.
What is COD?
Answer:
Chemical Oxygen Demand.

Question 12.
In which nation did Minamata disease occur?
Answer:
Japan.

Question 13.
What is deforestation?
Answer:
Removal decrease or deterioration of the forest area.

Question 14.
What is afforestation?
Answer:
The creation of forests in treeless regions is afforestation.

Question 15.
What is chipko movement?
Answer:
It is a movement of tree (forest) protection where local people hug trees when attempts are made to cut them. It was started by S. L. Bahuguna in forests of Tehri Garwhal.

Question 16.
Name the unit used for measurement of thickness of Ozone in a column of air.
Answer:
Dobson unit.

2nd PUC Biology Environmental Issues Two Marks Questions and Answers

Question 1.
Describe Eutrophication.
Answer:
It is a natural process of aging of water bodies due to rich supply of nutrients. In young water bodies water is cold, clear with moderate life forms. However, when abnormally high amount of nutrients are released from sewage, it results in excessive algal growth or bloom of microorganisms.

Question 2.
What are the various constituents of domestic sewage? Discuss the effects of sewage. discharge on a river.
Answer:
Sewage contains human and animal excreta, food residues, detergents and other organic wastes. It is always rich in bacteria and other biological pollutants. Discharge of sewage into a river, raise the BOD, leading to the killing of fishes and other aquatic life. Water polluted with sewage also become a potent source of many water borne diseases.

Question 3.
List all the wastes that you generate, at home, school or during your trips to other places, could you very easily reduce? Which would be difficult or rather impossible to reduce?
Answer:

Question 4.
Match the items given in column A and B:

Answer:
(a) – (ii),
(b) – (i),
(c) – (iii),
(d) – (iv).

2nd PUC Biology Environmental Issues Three Marks Questions and Answers

Question 1.
What is bio-magnifaction? Diagramatically represent the process of bio-magnification of DDT in an aquatic food chain.
Answer:
It is the process of accumulation of certain pollutants in tissues, with increased concentration, along the food chain. Most of the pesticides are non degradable and are persistent and get accumulated in increasing concentration, e.g. DDT is insoluble in water and is non- biodegradable. When it is extensively used, it goes into the soil through the rainwater.

From the soil, DDT passes into plants, in which DDT is found to be more concentrated than in soil. Experiments have revealed that in a food chain, DDT becomes more and more concentrated and accumulated when it passes from the lower to the higher trophic levels. The accumulation and concentration of DDT in each trophic level, on an average, increases by ten times.

Question 2.
Discuss the causes and effects of global warming. What measures need to be taken to control global warming?
Answer:
Causes of global warming are increasing concentration of greenhouse gases (ie., CO₂, CH₄, CFCs and N₂O) in the atmosphere.

1. Weather and climate: Global mean temperature rose by 0-6o C during the 20th century. It is going to increase further by 1-4° – 5-8°C between 1990 – 2100 AD.

2. Stratosphere and thermosphere: Warming of troposphere will cause cooling of stratosphere and thermosphere. The whole atmosphere will shrink. Cooling of stratosphere will increase the size of ozone holes and thinning of ozone shield at other places. Cooling of thermosphere will disrupt communications and the shielding effect of ionosphere.

3. Sea level change: It is believed that sea level has risen by 15cm during the 20th century, a rise of 1-2 mm every year. By the year 2100 AD, the global mean sea level is going to rise by 0-88m over that of 1990 sea level. Rise in sea level is due to thermal expansion of oceans as the temperature rises, melting of glaciers and Greenland ice sheets.

4. Range of species distribution: Each species has a particular range of temperature. Global warming will push tropics into temperate areas and temperate areas towards poles and higher altitudes in mountains A rise of 2°-5° C can cause pushing of temperate range vegetation some 250-600km towards the pole.

5. Food production: Rise in global temperature is going to have a negative impact on food production despite beneficial effect of CO₂ fertilization. The various reasons are increase in basal rate of respiration by plants

Lesser storge of food and hence less productivity
Explosive growth of weeds
Higher incidence of pathogens and pests
Increased evaporation of soil water and higher transpiration from plants resulting in water deficiency.

Question 3.
Write critical notes on the following:
(a) Eutrophication
(b) Biological magnification
(c) Ground water depletion and ways for its replenishment.
Answer:
(a) Eutrophication refers to the process of aging of a water body due to excessive growth of algae, plants and certain other aquatic organisms in the water body, due to nutrient enrichment particularly with nitrogen and phosphorus. As the lake’s fertility increases plant and animal life burgeons, and organic remains goes on accumulation at the bottom of lake. With passage of time the lake grows shallower and warmer, and finally converts into a piece of land

(b) Biological magnification: It is the phenomenon through which certain pollutants get accumulated in tissues in increasing concentration along the food chain. A classical example of biological magnification is the accumulation of DDT in the tissue of organisms of aquatic food chain. High concentration of DDT disturbs calcium metabolism in aquatic birds leading to the thinning of egg shells and their pre-mature breaking, eventually causing decline in bird population.

(c) Groundwater depletion and ways for its replenishment: Excessive use of ground water for drinking, irrigation and domestic purposes has resulted in its rapid depletion in various regions of the country leading to lowering of water table and drying of wells. Groundwater can be replenished by,

1. preventing run off losses of water by using contour cultivation, terrace farming, mulching and developing farm ponds.

2. adopting rain water harvesting techniques i.e., collection of rain water in check downs (bandhs), tanks and ponds (johads)

Question 4.
Discuss the role of women and communities in protection and conservation of forests.
Answer:
People’s participation has a long history in India. Bishnoi Community is known for its peaceful
co-existence with nature. In 1731a Bishnoi woman, Amrita Devi, her three daughters and hundreds of other Bishnois lost their lives for saving trees.

Chipko movement and Appiko movement are other examples of people’s participation in the conservation of forests. Presently, under the Joint Forest Management scheme (JFM), village and tribal communities are being involved in the development and protection of the forests.

Question 5.
With a labeled diagram explain the functioning of electrostatic precipitator. Electrostatic Precipitator

It is the most widely used method for removal of particulate matter; about 99% of particulate pollutants are removed from the exhaust of thermal power plant.
It has electrode wires and a stage of collecting plates.
The electrode wires are maintained at several thousand volts, which produce a corona that releases electrons.
These electrons get attached to the (dust) particles and give them a net negative charge within a very small fraction of a second.
The collecting plates are grounded and hence attract the charged particles.
The velocity of air between the plates must be low enough to allow the particles to fall on them.

Question 6.
What measures, as an individual, you would take to reduce environmental pollution?
Answer:
An individual can help in reducing environmental pollution by,

using eco-friendly products (e.g., paper bags, earthen cups etc.)
adopting reduce, rouse and recycle policy.
minimising the dependency on natural resources.
planting more trees.
adopting family planning measures.

Question 7.
Note on a case study of plastic wastes.
Answer:
As a remedy for plastic wastes, polyblend, a fine powder of recycled modified plastic was developed by experts from R.V. College of Engineering and K.K. Plastics. This mixture is mixed with the bitumen that is used to lay roads. Polyblend enhanced the bitumen’s water repellant properties and helped to increase road life by a factor of three.

Question 8.
What is jhum (slash and burn agriculture) cultivation? How it accounts for deforestation?
Answer:
Slash and Burn agriculture/Jhum cultivation: It is an agricultural technique in which an area of forest is cleared by cutting and burning and is abandoned to return to a more natural state over time’.

Question 9.
a) What is green house effect?
b) What are green house gases? Depict diagrammatically relative contribution of green house gases to total global warming.
Answer:
Green house gases : They are gaseous components of atmosphere which allow the short wave radiations to pass through but absorb the long wave heat (infra-red) radiations. Presence of green house gases (CO₂, CH₄, N₂O, CFCs) in the atmosphere, convert it into a window glass pane like cover around the earth (as found in a glass houses).

It allows most of the solar radiations which have shorter wave length (0 – 2 – 4 – 0nm) to reach up to earth’s surface. As the solar radiations are reflected from earth’s surface they are changed into long wave radiations. A part of this energy is re-radiated back to the surface of earth.

The downward flux of long wave radiation by green house gases is called green house flux. It is important in keeping the earth warm with an average or mean annual temperature of about 15° C. In the absence of this flux, the earth’s mean temperature would drop to 20°C at which temperature water will freeze and kill most life forms.

Effect of global warming:
Global warming, a consequence of higher concentration of green house gases, has the potential to affect weather and climate, stratosphere and thermosphere, rise in sea level, species distribution and food production.
1. Weather and climate: Global mean temperature rose by 0-6° C during the 20th century. It is going to increase further by 1 – 4° – 5 – 8°C between 1990 – 2100 AD.

3. Sea level change: It is believed that sea level has risen by IScm during the 20th century, a rise of 1 -2 mm every year. By the year 2100 AD, the global mean sea level is going to rise by 0-88m over that of 1990 sea level. Rise in sea level is due to thermal expansion of oceans as the temperature rises, melting of glaciers and Greenland ice sheets.

4. Range of species distribution: Each species has a particular range of temperature. Global warming will push tropics into temperate areas and temperate areas towards poles and higher altitudes in mountains Arise of 2°-5° C can cause pushing of temperate, range vegetation some 250-600km towards the pole.

2nd PUC Biology Environmental Issues Five Marks Questions and Answers

Question 1.
Write a note on groundwater depletion and ways for its replenishment.
Answer:
Ground water depletion and ways for its replenishment: The level of ground water has decreased in the recent years. The source of water supply is rapidly diminishing each year, because of an increase in the population and water pollution. To meet the demand of water, wafer is withdrawn from water bodies such as ponds, rivers etc. As a result, the source of groundwater is depleting.

This is because the amount of groundwater being drawn for human use is more than the amount replaced. Lack of vegetation cover also results in very small amounts of water seeping through the ground. An increase in water pollution is another factor that has reduced the availability of ground water.
Measures for replenishing ground water:

Preventing over-exploitation of ground water.
Optimizing water use and reducing water demand.
Rain water harvesting.
Preventing deforestation and plantation of more trees.

Question 2.
What are algal blooms? How are they formed? Give the harmful effects of formation of algal blooms in an aquatic body.
Answer:
Domestic sewage contains nutrients like nitrogen and phosphorus which favours the excessive growth of algae (free floating) called algal bloom.
The harmful effects :

Deterioration of water quality and imbalance of water ecosystem.
Fish mortality rate increases.
Some bloom forming algae are extremely toxic to human beings and animals.

Question 3.
What is water pollution? Describe sewage pollution briefly.
Answer:
If is the undesirable change in physical, chemical and biological characteristics of water resources adversely affecting human’health and life of animals.
The four main types of water pollution are,

Sewage pollution.
Industrial pollution.
Biocide pollution.
Thermal pollution.

Sewage pollution: Sewage is a biodegradable pollutant concentrated with human faeces, animal excreta, food residues, domestic wastes, detergents and several dissolved chemicals (sulphates, phosphates, alkalies, nitrates, acids). Sewage also contains pathogenic bacteria, eggs, cysts and spores of parasites. Sewage is discarded from homes, hotels, and choultries and hostels getting dumped constantly into nearby water resources like lakes, ponds, rivers and oceans causing water pollution.

Effects :
Presence of sewage increases turbidity of water, which reduces solubility of oxygen and penetration of light, both of which adversely affect the photosynthetic and respiratory activities of aquatic organisms.

Sewage water provides good breeding ground for mosquitoes and favours growth of pathogenic bacteria and parasites. Thus it forms a source for the outbreak of diseases like malaria, typhoid, cholera, jaundice and dysentery.

Sewage dumping causes sudden nutrient enrichment resulting in plankton bloom. This process is called eutrophication. It creates biological oxygen demand (BOD), and oxygen shortage to fishes, which suffocate to death.
To prevent these effects, sewage treatment should be done before letting it out.

Question 4.
Discuss briefly the following :
(a) Radioactive wastes,
(b) e-wastes,
(c) Municipal solid wastes.
Answer:
(a) Radioactive wastes: Radiation, that is given off by nuclear waste is extremely damaging to organisms, because it causes mutations at a very high rate. At high doses, nuclear radiation is lethal but at lower doses, it creates various disorders, the most frequent of all being cancer. Therefore, nuclear waste is an extremely potent pollutant and has to be dealt with utmost caution.

It has been recommended that storage of nuclear waste, after sufficient pre-treatment, should be done in suitable shielded containers buried within the rocks, about 500 m deep below the earth’s surface.

(b) e-wastes :
e-wastes are generated in the developed countries and are sent to developing countries where certain metals like gold, nickel, silicon, copper, iron, etc. are recovered from them.

Then recycling is done manually and hence, the workers are exposed to the toxic substances.

Municipal solid wastes are burnt to reduce the volume, but they are not burnt completely and the open dumps serve as the breeding ground for flies and rats.
Sanitary landfills have been adopted as an alternative to open burning dumps.
Municipal wastes are incinerated and the heat emitted is used to generate electricity.
They are also recycled for various components.
Fly ash is used in construction industry or buried as landfills; it is also used for soil amendment as it increases water retention and aeration of soil.
e-wastes are buried as landfills or incinerated and they are also recycled.

Question 5.
What is deforestation? Explain importance of people’s participation in Forest conservation with reference to Amrith Devi Bishnoi’s case study.
Answer:
Removal, decrease or deterioration of forested area is called deforestation. Deforestation has been going on since the beginning of civilization. The decline has been maximum in the tropics (more than 40%) and minimum in temperate regions (1 % or less).

People’s participation has a long history in India. In 1731, the King of Jodhpur in Rajasthan asked one of his ministers to arrange wood for constructing a new palace. The minister and workers went to a forest near a village, inhabited by Bishnois, to cut down trees. The Bishnoi community is known for its peaceful co-existence with nature.

The effort to cut down trees by the King was thwarted by the Bishnois. A Bishnoi woman Amrita Devi showed exemplary courage by hugging a tree and daring King’s men to cut her first before cutting the tree. The tree mattered much more to her than her own life.

Sadly, the King’s men did not heed to her pleas, and cut down the tree along with Amritha Devi. Her three daughters and hundreds of other Bishnois followed her, and thus lost their lives saving trees. Nowhere in history do we find a commitment of this magnitude when human beings sacrificed their lives for the cause of the environment.

The Government of India has recently instituted the Amrita Devi Bishnoi Wildlife Protection Award for individuals or communities from rural area that have shown extraordinary courage and dedication in protecting wildlife.

Question 6.
Explain five effects of water pollution.
Answer:
Water Pollution: It is the undesirable change in physical, chemical and biological characteristics of water resources adversly affecting human health and life of domestic animals.
The four main types of water pollution are

Sewage pollution.
Industrial pollution.
Biocide pollution.
Thermal pollution.

Sewage Pollution: Sewage is a biodegradable pollutant concentrated with human faeces, animal excreta, food residues, domestic wastes, detergents and several dissolved chemicals (sulphates, phosphates, alkalies, nitrates, acids). Sewage also contains pathogenic bacteria, eggs, cysts and spores of parasites.

Sewage is discarded from homes, hotels, and choultries and hostels being dumped constantly into nearby water resources like lakes, ponds, rivers and oceans causing water pollution.

Effects:
Presence of sewage increases turbidity of water, which reduces solubility of oxygen and penetration of light, both of which adversely affect the photosynthetic and respiratory activities of aquatic organisms.

Sewage water provides good breeding ground for mosquitoes and favours growth of pathogenic bacteria and parasites. Thus it forms a source for the out break of diseases like malaria, typhoid, cholera, jaundice and dysentery.

To prevent these effects, sewage treatment should be done before letting it out.

Question 7.
What is global warming? Mention its causes, effects and control measures.
Answer:
Global warming, a consequence of higher concentration of green house gases, has the potential to affect weather and climate, stratosphere and thermosphere, rise in sea level, species distribution and food production.

1. Weather and climate: Global mean temperature rose by 0-6° C during the 20th century. It is going to increase further by 1-4° – 5-8°C between 1990 – 2100 AD.

3. Sea level change: It is believed that sea level has risen by IScm during the 20th century, a rise of 1 – 2 mm every year. By the year 2100 AD, the global mean sea level is going to rise by 0-88m over that of 1990 sea level. Rise in sea level is due to thermal expansion of oceans as the temperature rises, melting of glaciers and Greenland ice sheets.

4. Range of species distribution: Each species has a particular range of temperature. Global warming will push tropics into temperate areas and temperate areas towards poles and higher altitudes in mountains Arise of 2°- 5° C can cause pushing of temperate, range vegetation some 250 – 600km towards the pole.

Lesser storge of food and hence less productivity.
Explosive growth of weeds.
Higher incidence of pathogens and pests.
Increased evaporation of soil water and higher transpiration from plants resulting in water deficiency.

Question 8.
a) What are radioactive wastes? Mention how radioactive wastes are disposed,
b) Write short notes on e-wastes.
Answer:
(a) Radioactive wastes: Radiation, which is given off by nuclear waste is extremely damaging to organisms, because it causes mutations at a very high rate. At high doses nuclear radiation is lethal but at lower doses, it creates various disorders, the most frequent of all being cancer. Therefore, nuclear waste is an extremely potent pollutant and has to be dealt with utmost caution.

It has been recommended that storage of nuclear waste, after sufficient pre-treatment, should. be done in suitable shielded containers, buried within the rocks, about 500 m deep below the earth’s surface.

(b) Electronic wastes (e-wastes): e-wastes are generated in the developed countries and are sent to developing countries where certain metals like gold, nickel, silicon, copper, iron, etc. are recovered from them.

Then recycling is done manually and hence, the workers are exposed to the toxic substances.