Bihar Board Class 12 Biology Solutions Chapter 16 Environmental Issues Textbook Questions and Answers, Additional Important Questions, Notes.
BSEB Bihar Board Class 12 Biology Solutions Chapter 16 Environmental Issues
Bihar Board Class 12 Biology Environmental Issues Text Book Questions and Answers
What are the various constituents of domestic sewage? Discuss the effects of sewage discharge on a river.
The various constituents of domestic sewage are :
(a) Suspended impurities, e.g., sand, silt and clay.
(b) Colloidal material, e.g., fecal matter, bacteria, cloth and paper fibres.
(c) Dissolved materials, e.g., nutrients (nitrates, ammonia, phosphate, sodium, calcium).
Effects of sewage discharge on a river :
(a) When sewage is discharged on a river, micro-organisms involved in biodegradation of organic matter in the receiving water body consume a lot of oxygen, and as a result there is a sharp decline in dissolved oxygen down stream from the point of sewage discharge. This causes mortality of fish and other aquatic organisms.
(b) Due to the presence of large amount of nutrients in water also causes excessive growth of planktonic algae, called an algal bloom. These impart a distant colour to the water bodies. Algal bloom cause deterioration of the water quality and fish mortality. Some algal bloom are extremely toxic to human beings and animals.
(c) Some aquatic weed such as water hyacinth (Eichhomiacrassipes) grow faster than our ability to remove them in the water bodies. They grow abundantly and lead to an imblanace in the ecosystem dynamics of the water body.
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?
List of wastes generated at home :
(b) Vegetable and fruit peels
(c) Plastic bags
(e) Waste cloth
(f) Plastic wastes
(g) Waste tins etc.
List of waste generated at school :
(b) Fruit peels
(c) Shaving of pencil
(d) Refill of ball or gel pens
List of waste generated during a trip :
(b) Plastic bags, bottles, etc.
(c) Remains of fruits and
(d) Waste cloth other eatables
No, it is very difficult to reduce. We cannot reduce peels of vegetables and fruits, polythene bags, paper, etc.
Discuss the causes and effects of global warming. What measures need to be taken to control global warming?
Causes of global warming :
(a) Increase use of fossil fuels and burning of toxic materials.
(c) Increase in human population thereby leading to deforestation.
(d) Increase in emission of greenhouse gases into the atmosphere.
Effects of global warming :
(a) Rise in temperature leading to deleterious changes in the environment.
(b) Result in odd climatic changes.
(c) Lead to increased melting of polar ice caps as well as of other places like the Himalayan snow caps.
(d) Rise in sea level that can submerge many coastal areas.
Measures to control global warming :
(a) Cutting down of fossil fuels.
(b) Improving efficiency of energy usage, reducing deforestation.
(c) Planting trees.
(d) Slowing down the growth of human population.
(e) Reduction of emission of greenhouses gases into the atmosphere.
Match the items given in Column A and B :
|Column A||Column B|
|(a) Catalytic convertor||(i) Particulate matter|
|(b) Electrostatic precipitator||(ii) Carbon monoxide and nitrogen oxide|
|(c) Earmuffs||(iii) High noise level|
|(d) Landfills||(iv) Solid wastes|
(a) – (ii),
(b) – (i),
(c) – (iii),
(d) – (iv).
Write critical notes on the following :
(b) Biological magnification
(c) Groundwater depletion and ways for its replenishment
(a) Eutrophication – It is the natural ageing of a lake by biological enrichment of its water. Stream draining into the lake introduce nutrients such as nitrogen and phosphorus. Sewage and industrial wastes are also rich in nitrate and phosphates, which act as plant nutrients. They overstimulate the growth of algae, causing unsightly scum and unpleasant odours, and robbing the water of dissolved oxygen vital to other aquatic life. Other pollutants flowing into a lake may poison whole populations of fish, whose decomposing remain further deplete the water’s dissolved oxygen content.
(b) Biological magnification – It refers to increase m concentration of the toxinant at successive trophic levels. This is due to when a toxic substance accumulated by an organism cannot be metabolised or excreted, and a thus passed on to the next trophic level. This phenomenon is well-known for mercury and DDT.
(c) Groundwater depletion and ways for its replenishment – Although water is a renewable resource yet it needs some time for replenishing. The level of groundwater is falling day by day due to increasing irrigation practices. Million of people live in one big city that cover an area of one or two hundred square km. it is very difficult to supply fresh water to millions of people. Due to this enormous pressure is exerted on the groundwater resources of that area.
Major sources of groundwater are contaminated due to leaking pits, leaking industrial waste ponds etc. Groundwater can be replenished by growing the type of crops in those areas where there is scarcity of water, minimum use of water, rainwater harvesting and allowing rainwater to seep into the soil. Check of leaking pits, leaking industrial waste, etc.
Why ozone layer forms over Antarctica? How will enhanced ultraviolet radiation affect us?
Ozone layer forms over Antarctica because it is the endpoint of the southern hemisphere and the layer of ozone is thinner here.
Effects of UV radiations: UV-B damages DNA and mutation may occur. It causes ageing of skin, damage to skin cells and various types of skin cancers. In the human eye, cornea absorbs UV-B radiation, and a high doses of UV-B causes inflammation of cornea called snow-blindness cataract etc. Such exposure may permanently damage the cornea.
Discuss the role of women and communities in protection and conservation of forests,
Role of women and communities in protection and conservation of forests :
– In 1731, a Bishnoi women Amrita Devi showed exemplary courage by hugging a tree and daring the king’s (King of Jodhpur in Rajasthan) men’s who wanted to cut the trees to arrange wood for constructing a new palace, to cut her first before cutting the tree. The tree mattered much more to her than her own life. However, the king’s men did not pay heed to her plea and cut down the tree along with Amrita Devi.
Her three daughters and hundreds of other Bishnois followed her, and thus, lost their lives saving trees. The Government of India has recently instituted the Amrita Devi Bishnoi Wildlife Protection Award for individuals or communities from rural areas that have shown extraordinary courage and dedication in protecting the wildlife.
– In 1974, local women of Garhwal Himalayas started the Chipko Movement. In this movement women showed enormous bravery in protecting trees from the axe of contractors by hugging them.
– In 1980s the Government of India introduced the concept of Joint Forest Management (JFM) so as to work closely with the local communities for, protecting and managing forests. The communities get benefit of various forest products (e..g., fruits, gum, rubber, medicine, etc.), in return for their services to the forest. In this way the forests can be conserved in a better way.
What measures, as an individual, you would take to reduce environmental problems?
Measures to reduce environmental problems, as an individual:
- Stop using polythene bags.
- Conserve water by not misusing it.
- Walk a short distance instead of using private vehicle.
- Use public transport instead of private vehicle.
- Sort out the biodegradable and non-biodegradable waste. Throw the waste in separate boxes.
- Prefer to use recyclable items.
- Never throw garbage in drains.
- Seal leaking taps and use less water for drainage.
Discuss briefly the following :
(a) Radioactive wastes
(b) Defunct ships and e-wastes
(c) Municipal solid wastes.
(a) Radioactive wastes – Radioactive waste is generated from nuclear plants. The radiation given off by nuclear waste is extremely damaging to biological organisms, became it causes mutations to occur at a very high rate. Nuclear radioactive, at high doses, is lethal but at lower doses, it creates various disorders such as cancer. Thus, nuclear waste is an extremely potent pollutant. The storage of nuclear waste, after sufficient pre-treatment, should be done in suitably shielded containers burried within the rocks, about 500m deep below the earth’s surface.
(b) Defunct ships and e-wastes – Defunt ships refers to those articles which are no longer operating or dead. E-wastes refers to waste of irreparable computers and electronic goods. E-wastes are either buried in landfills on incinerated. Most of the developing countries such as China, India and Pakistan import e-wastes from developed countries where metals like copper, iron, silicon, nickel and gold are recovered during cycling process.
In developing countries recycle of e-wastes is carried out by manual participation, thereby exposing workers to toxic substances present in e-wastes. However, the only solution to e-waste is recycling which has to carried out in an environment-friendly manner.
(c) Municipal solid wastes – There are wastes from homes, offices, stores, schools, hospitals, etc. that are collected and disposed by the municipality. The wastes mostly comprise of paper, food wastes, plastics, glass, metals, rubber, leather, textile etc. Some waste is burnt while the remaining in dumped in a landfill.
What initiatives were taken for reducing vehicular air pollution in Delhi? Has air quality improved in Delhi?
Initiatives taken for reducing air pollution in Delhi are as follows :
(a) Switching over the entire fleet of public transport, i.e., buses, from diesel to CNG. This-was because CNG burns more efficiently unlike petrol or diesel and a very little is left unburnt. Also CNG is cheaper than petrol or diesel and cannot be siphoned off by thieves and adultered like petrol or diesel.
(b) Phasing out of old vehicles.
(c) Use of unleaded petrol.
(d) Use of low-sulphur petrol and diesel.
(e) Use of catalytic converters in vehicles.
(f) Application of stringent pollution-level norms for vehicles, etc.
(g) The government of India through a new auto fuel policy has laid out a road map to cut down vehicular pollution in Indian cities. For example, Euro II norns have been introduced. This norm stipulates that sulphur be controlled at 350 ppm in diesel and 150 ppm in petrol. Aromatic hydrocarbons are to be contained at 42 per cent of the concerned fuel. Due to the efforts of the Delhi government, the air quality of Delhi has significantly improved. According to an estimate, a substantial fall in CO2 and SO2 level has been found in Delhi between 1997 and 2005.
Discuss briefly the following: ‘
(a) Greenhouse gases
(b) Catalytic converter
(c) Ultraviolet B.
(a) Greenhouse gases – Carbon dioxide and methane are commonly known as greenhouse gases because they are responsible for the greenhouse effect. These gases absorb longwave (infrared) radiation from the earth and emit it again towards the earth. The cycle continues till the earth’s surface has no longwave radiation to emit.
(b) Catalytic converter – Catalytic converters have expensive metals namely platinum-palladium and rhodium as catalysts in them. These converters are fitted into automobiles for reducing emission of poisonous gases. As the exhaust passes through the catalytic converter, unburnt hydrocarbon are converted into carbon dioxide and water, and carbon monoxide and nitric oxide are changed to carbon dioxide and nitrogen gas, respectively. Vehicles fitted with catalytic converter should use unleaded .petrol because lead in the petrol inactivates the catalyst.
(c) Ultraviolet B – UV-B radiations are of larger wavelengths. These rays are highly injurious to live organisms. The penetrative of these rays into the surface of the earth can damage DNA and lead to mutation. It causes ageing of skin, damage .to skin cells and various types of skin cancers. The cornea of the human eye, absorbs UV-B can cause inflammation of cornea, called snow-blindness cataract, etc. Such exposure may permanently damage the cornea.
Bihar Board Class 12 Biology Environmental Issues Additional Important Questions and Answers
Very Short Answer Type Questions
What is pollution?
The undesirable change in physical, chemical or biological characteristics of air, land, water or soil is called pollution.
What are pollutants?
Agents that bring about changes in the abiotic components of the earth are called pollutants.
Which Act was passed by the Government of India to protect and improve the quality of our environment? ,
Environment (Protection) Act, 1986.
What are the affects of air pollutants of animals and human beings?
Air pollutants affect the respiratory system of humans and of animals. Harmful effects depend on the concentration of pollutants, duration of exposure and the organism.
Which precipitator can remove 99 per cent particulate matter present in the exhaust from a thermal power plant?
What is the work of the scrubber in an electrostatic precipitator?
The scrubber removes gases like sulphur dioxide.
What is the size of the particulate which can cause greatest harm to human health?
2.5 micrometres or less in diameter (PM 2.5).
What harm can the same particulate do to the human body?
It can cause irritation, inflammations and damage the lungs and lead to premative deaths.
What is the full form of CNG?
Compressed Natural Gas.
What are the major cause of atmospheric pollution in metro cities?
What type of petrol is used in catalytic converter?
Why is the above petrol used?
Because lead in the petrol inactivates the catalyst.
Has the quality of air in Delhi improved or reduced after the introduction of CNG?
What is noise?
Noise is undesired high level of sound.
How much sound is produced by the take-off of a jet or rocket?
150 dB or more.
What are the affects of noise?
Noise can permanently damage hearing abilities of humans. It can also cause sleeplessness, increased heart beating, alternated breathing patterns, thus considerably stressing humans.
State a way to reduce noise is the industries.
By use of sounds absorbent materials or by muffling noise.
Which Act was passed by the Government of India to safeguard our water resources?
Water (Prevention and Control of Pollution) Act, 1974.
What are planktonic algae?
What is the full form of BOD?
Biochemical Oxygen Demand.
Short Answer Type Questions
Explain in brief electrostatic precipitator.
Ans. The electrostatic precipitator can remove 99 per cent particulate matter present in the exhaust from a thermal ‘power plant. The precipitator has electrode wires that are maintained of several thousand volts, which produce corona that release electrons these electrons attach to dust particles giving them a net, negative charge. The collecting plates are grounded and attract the charged dust particles.
The velocity of air between the plates must be low enough, be allow dust to fall. A scrubber inside the precipitator removes gases like sulphur dioxide, In a scrubber, the exhaust is passed through a spray of water or lime.
What is the major cause for atmospheric pollution in metro cities? How can this pollution, reduced? ,
Automobiles are a major cause of atmospheric pollution in metro cities. The pollution can be reduced by proper maintenance of automobiles along with use of lead-free petrol or diesel.
What laws should be enforced to protect ourselves from noise pollution?
stringent following of laws laid down in relation to noise like delimitation of horn-free zones around hospitals and schools permissible sound-levels of crackers and of .loudspeakers, timings after which loudspeakers cannot be, played,.etc. need to be enforced to protect ourselves from noise pollution.
What are the effects discharge of sewage into, a river?
When sewage is discharged into river, micro-organisms,; involved in biodegradation of organic matter .in the receiving, water bodies consume a lot of oxygen, and thus, there is a sharp .decline in dissolved oxygen downstream from the point of sewage discharge. This cause mortality of fish and other aquatic creatures.
What are the effects of the presence of large amount of nutrients in water?
Presence of large amount of nutrients in water causes excessive growth of planktonic alage called algal bloom which imparts a distant colour to the water quality and fish mortality. some alage bloom are also extremely toxic to human beings and animals.
Why are plants of water hyacinth called the worlds most problematic aquatic weed?
plants of water hyacinth are called the most problematic Aquatic weed because these plant grow abundantly in eutrophic water bodies, and lead to an imbalance in the ecosystem dynamics of the water bodies.
What are the effect of dIsposal of sewage from honies and hospitals directly ihto water bodies? –
Sewage in homes and Iiospitas contain many undesirable pathogenic micro-organisms, and if disposed directly into water can cause outbreak of serious diseases, such as, dysentery, typhoid, jaundice, cholera, etc.
What are the components of wastewater from industries like petroleum paper manufacturing, metal extraction and processing and chemical manufacturing?
Wastewater of the above industries contains toxic substances and a variety of organic compounds.
What is cultural or accelerated eutrophication?
Pollutants from in activities like effluent from industries and homes can radically accelerate the ageing process of water bodies. This phenomenon is called cultural or accelerated eutrophication.
What are the effects of wastewater of thermal power plants if disposed directly into water bodies?
Thermal wastewater if disposed directly into water bodies eliminates or reduces the number of organisms sensitive to high temperature, and may exchange the growth of plant and fish in extremely cold areas hut, only after causing damage to the indigenous flora and fauna.
What are municipal solid wastes?
Municipal solid wastes are waste from homes, offices, stores. schools, hospitals, etc. that are collected and disposed by the municipality. These wastes generally comprise paper. food wastes. plastics. glass, metals, rubber, leather, textile. etc.
What are sanitary landfills?
Sanitary landfills are open pits. The wastes are dumped in a depression or trench after compaction and covered with dirt every day.
What steps should be taken by human beings to solve environmental issues?
All waste that is generated by us should be categorised into three types:
The biodegradable materials should be put into deep pits in the ground and be left for natural breakdown. Only the non-biodegradable waste should be disposed off. The need to reduce our garbage generation should be a prime goal.
What is organic farming?
Organic farming is a cyclical, zero-waste procedure, where waste products from one process are cycled in as nutrients for other processes. This allows the maximum utilisation of resource and increases the efficiency of production.
What is global warming? What are its effects?
Increase in the level of greenhouse has led to considerable heating of earth leading to global warming.
Effects of global warming :
- Due to global warming the temperature of the earth has increased by 0.6°C.
- The rise is temperature can lead to deleterious changes in the environment and resulting in odd climatic changes.
- It can lead to melting of polar ice caps as well as of other places like the Himalayan snowcaps.
- It can rise the sea level that can submerge many coastal areas.
What has led to the enhancement of ozone degradation? How?
Chlorofluorocarbons (CFCs) has led to the degradation of the ozone layer. CFCs discharged in the lower part of atmosphere move upward and reach stratosphere. In stratosphere, UV rays acts on them releasing Cl atoms. Cl degrades ozone releasing molecular oxygen, with these atoms acting merely as catalysts. Cl atoms are not consumed in the reaction. Thus, CFCs are added to the stratosphere which have permanent and continuing affects on ozone levels.
What are the effects of water Jogging?
Irrigation without proper drainage of water leads to waterlogging in the soil besides affecting the crops, waterlogging draws salt to the surface of the soil. The salt is then deposited as a thin crust on the land surface or starts collecting at the roots of the plants. This increased salt content is inimical to the growth of crops and is extremely damaging to agriculture.
How does deforestation occur?
Deforestation occurs due to various human activities. These are as follows:
- Conversion of forest to agricultural land so as to feed the growing human population.
- Trees are used for timber, firewood, cattle ranching and for several other purposes.
- Slash and burn agriculture also called Jhum cultivation in northeastern state of India, has also contributed to deforestation.
What is reforestation?
Reforestation is the process of restoring a forest that once existed but was removed at some point of time in the past. In a deforested area, reforestation may occur naturally. Reforestation can be speeded by planting trees with due to consideration to biodiversity that earlier existed in that area.
Long Answer Type Questions
With an example explain the importance of organic farming.
Organic farming is a cyclical, zero-waste procedure, where waste products from one process are cycled in as nutrients for other processes. This enhances the maximum utilization of resources and increases the efficiency of production. For example, a farmer of Sonipat, Haryana, Ramesh Chandra Dagar, includes bee-keeping, dairy management, Vater harvesting, compositing and agriculture in a chain of. processes, which support each other and allow an extremely economical and sustainable venture. Cattle excreta (dung) are “used as dung in place of chemical fertilizers for crops; Crop waste is used to create compost, which can be used as a natural fertilizer or can be used to generate natural gas for satisfying the energy needs of the farm.’
Explain how, a plastic sack manufacturer, AhmedKhan, in Bangalore has solved the problem of ever-increasing plastic waste.
Ahmed Khan, a plastic sack manufacturer of Bangalore has been producing plastic sacks for 20 years. After some years, his company developed a fine powder of recycled modified plastic, polyblend. This mixture is mixed With the bitumen that is used to lay roads: In collaboration with R.V. Allege of Engineering and the Bangalore City Corporation, Ahmed Khan proved that brands of polyblend and bitumen,” When used to lay roads; enhanced the bitumen’s water-repellant properties and helped to increase road life by a factor of three. using Khan’s technique, by the year 2002, more than 40 km of road in Bangalore has already being laid.
One Word Type Questions
What is the natural aging of a lake called? ‘
What is increase in concentration of the toxicant of successive trophic levels called?
In which year was the Water Act passed?
What are the agents which bring about undesirable changes in the environment called?
In which year was the Environment Act passed?
What is the fine powder of recycled modified plastic called?
Name the pollutant that has degraded the ozone layer.
Name one greenhouse gas.
In which year was the Montreal Protocol signed?
What is the process of restoring a forest called?