Solutions-Class-12-Biology-Chapter-15-Biodiversity, Conservation and Environmental Issues-Maharashtra Board

Biodiversity, Conservation and Environmental Issues

Maharashtra Board-Class-12th-Biology-Chapter-15


Question 1. Choose the correct option

(1) Observe the graph and select correct option.

(a) Line A represents, S = CA2

(b) Line B represents, log C= log A + Z log S

(c) Line A represents, S = CAZ

(d) Line B represents, log S= log Z + C log A

Answer :

(c) Line A represents, S = CAZ

(2) Select odd one out on the basis of Ex situ conservation.

(a) Zoological park

(b) Tissue culture

(c) Sacred groves

(d) Cryopreservation

Answer :

(a) Zoological park

(3) Which of the following factors will favour species diversity?

(a) Invasive species

(b) Glaciation

(c) Forest canopy

(d) co extinction

Answer :

(a) Invasive species

(4) The term “terror of Bengal’ is used for ___________.

(a) algal bloom

(b) water hyacinth

(c) increased BOD

(d) eutrophication

Answer :

(b) water hyacinth

(5) CFC are air polluting agents which are produced by ___________.

(a) Diesel trucks

(b) Jet planes

(c) Rice fields

(d) Industries

Answer :

(b) Jet planes

Question 2. Very short answer type questions.

(1) Give two examples of biodegradable materials released from sugar industry.

Answer :

(i) Bagasse : Bagasse, a dry pulpy residue from sugarcane juice extraction, is a fibrous material used for bioenergy and paper production.

(ii) Molasses : Molasses, the liquid left after sugar extraction, contains residual sugars and organic compounds and can be used in animal feed, fermentation substrates, and industrial applications.

Both materials have various uses. These materials are biodegradable, meaning they can naturally break down over time without causing harm to the environment. 

(2) Name any 2 modern techniques of protection of endangered species.

Answer :

  • Tissue culture
  • Cryopreservation.

(3) Where was ozone hole discovered?

Answer :

Ozone hole was discovered in Antarctica.

(4) Give one example of natural pollutant.

Answer :

Volcanic ash is a natural pollutant.

(5) What do you understand by EW category of living being?

Answer :

A species that becomes extinct in the wild (EW) is referred to as an EW category; its individuals can only be found in captivity or as a naturalized population outside of its historic range because of extensive loss of habitat.

Question 3. Short answer type questions.

(1) Dandiya raas is not allowed after 10.00 pm. Why?

Answer :

Dandiya rass involves loudspeakers that produce noise pollution. It is an undesirable loud sound that may be harmful to the hearing and general health. Noise is classified as an air pollution under the Air (Prevention and Control of Pollution) Act 1981, as amended in 1987. According to the legislation, noise after 10 p.m. is prohibited since many individuals may be sleeping. Therefore, Dandiya Raas is not allowed after 10 p.m.

(2) Tropical regions exhibit species richness as compared to polar regions. Justify.

Answer :

  • Tropical regions have a higher species richness than polar regions due to thicker vegetation, sunlight, and humidity, while polar regions are covered in snow and have few animal species due to adaptations.
  • Species richness is a latitudinal gradient, with higher levels at lower latitudes and a steady decline towards the poles.
  • Therefore, tropical regions show more species richness.

(3) How does genetic diversity affect sustenance of a species?

Answer :

  • Genetic diversity is crucial for a species' sustenance as it allows it to adapt to environmental changes.
  • The large variation in gene sets allows individuals or populations to endure environmental stress.
  • Some individuals have better capacity to endure pollution, while others show infertility or death from the same conditions.
  • Natural selection, which leads to the loss of genetic diversity in specific habitats, allows those able to survive and adapt to these changes.
  • This process, known as natural selection, can significantly impact the sustenance of some species.

(4) Green house effect is boon or bane? Give your opinion.

Answer :

  • The natural greenhouse effect is good, it is a boon but human enhanced greenhouse effect is a bane.
  • In the absence of an atmosphere, Earth's surface temperature would be about -18 °C, or 0 °F, which is too cold for sustaining life.
  • The greenhouse effect, a natural phenomenon that helps Earth maintain its habitability, is a result of the presence of greenhouse gases like water vapor, carbon dioxide, methane, and nitrogen oxides.
  • These gases absorb infrared radiation from Earth and warm the atmosphere to its average temperature of 15°C (60°F).
  • However, human activities have significantly increased the proportion of greenhouse gases, leading to global warming.
  • The greenhouse effect was once a boon before industrialization and automobile invention, but its impact has become increasingly severe, making it a significant issue. Thus, now greenhouse effect has become a bane.

(5) How does CO cause giddiness and exhaustion?

Answer :

  • Carbon monoxide is tasteless, colourless and odourless gas, therefore its presence goes unnoticed.
  • It can inhibit the blood's ability to carry oxygen to body tissues.
  • Supply of oxygen to vital organs such as the heart and brain is affected due to presence of CO.
  • When CO is inhaled, it combines with the oxygen carrying haemoglobin of the blood to form carboxyhaemoglobin. Once combined with the haemoglobin, that haemoglobin is no longer available for transporting oxygen.
  • The symptoms of CO poisoning are headache, nausea, giddiness, etc.

(6) Name two types of particulate pollutants found in air. Add a note on ill effects of the same on human health.

Answer :

  • Particulate pollutants types include mist, dust, fumes, smoke particles, smog, pesticides, heavy metals, and radioactive materials.
  • Fine dust particles can harm the lungs' sensitive tissues.
  • Construction, demolition, and traffic can all lead to dust pollution. Dust can also be released naturally, such as by wind or volcanic eruptions.
  • Smoke and smog are the most harmful particle air pollutants, leading to respiratory issues such as emphysema and asthma.

Question 4. Long answer type questions.

(1) Montreal protocol is an essential step. Why is it so?

Answer :

  • Montreal Protocol was an international treaty signed at Montreal in Canada in 1987.
  • Later many more efforts have been made and protocols have laid down definite roadmaps separately for developing and developed countries.
  • All of these initiatives were aimed at lowering CFC emissions and other ozone damaging chemicals.
  • All nations recognized that ozone depletion might result in the penetration of damaging UV radiations to the earth's surface, which is extremely dangerous for flora, animals, and, most importantly, humans. Therefore, quick action was needed to mitigate this impact.
  • The Montreal Protocol was a really excellent action because the ozone layer has improved significantly since 1987.

(2) Name any 2 personalities who have contributed to control deforestation in our country. Elaborate on importance of their work.

Answer :

Two personalities who have contributed to control deforestation in our country are Saallumara Thimmakka from Karnataka and Moirangthem Loiya from Manipur.

(i) Saalumarada Thimmakka:

  • Saalumarada Thimmakka, an Indian environmentalist, is known for her efforts in reforestation.
  • She planted 385 banyan trees along a 4-kilometer stretch of highway between Hulikal and Kudur, providing shade, oxygen, and habitat for various species. She has also planted nearly 8,000 other trees, further enhancing green cover in her region.
  • Thimmakka's dedication has earned her the National Citizens Award of India and the Padma Shri in 2019.

Importance of Her Work:

  • Thimmakka’s efforts demonstrate that individual determination and community involvement can make a substantial impact on reforestation.
  • By planting and nurturing trees, she has not only mitigated deforestation but also improved the local environment and ecosystem.

(ii) Moirangthem Loiya:

  • Moirangthem Loiya, a Manipur native, dedicated 17 years to reforestation in the Punshilok Forest.
  • The 300-acre Punshilok Forest, once lush and diverse, had lost its former glory due to deforestation.
  • Loiya planted a variety of trees, including bamboo, oak, ficus, teak, jackfruit, and magnolia.
  • Today, the Punshilok forest has over 250 plant varieties, 25 of which are bamboo, and is a sanctuary for various animal species.

Importance of His Work: His dedication to reforestation not only revived the ecosystem but also provided a thriving habitat for wildlife.

(3) How BS emission standards changed over time? Why is it essential?

Answer :

  • As city life evolved and there was an increase in vehicle traffic, particularly in megacities, BS emission requirements changed throughout time.
  • Following Delhi's designation as the most polluted city in terms of air quality, the Indian government implemented a number of initiatives.
  • A new fuel strategy was announced, establishing Bharat Stage Emission Standards (BS). The purpose of these regulations was to lower the sulfur and aromatic levels in gasoline and diesel. The engines of vehicles were also updated.
  • Emission standards known as Bharat Stage (BS) are comparable to Euro standards and have developed in a manner akin to that of Bharat Stage II (BS II) to BS VI between 2001 and 2017.
  • In 2001, Bharat stage II emission norms were set for CNG and LPG vehicles in Delhi to save the population. This reduced sulfur emissions, with diesel and petrol levels controlled at 50 ppm and 150 ppm respectively.
  • Aromatic hydrocarbons were reduced by 42%. However, Delhi was declared the world's worst air-polluted city in 2016, prompting the Indian government to adopt BS VI in 2018, reducing CO2 and SO2

(4) During large public gatherings like Pandharpur vari mobile toilets are deployed by the government. Explain how this organic waste is disposed.

Answer :

  • The toilets deployed at Pandharpur at the time of vari are of the Ecosan type.
  • These closed systems, without water, are an alternative to leach pit toilets.
  • After filling up the pit, they are sealed for 8-9 months, allowing feces to compost to organic manure.
  • This method is practical, efficient, and cost-effective for human waste disposal.
  • Also, open-air defecation is prohibited which can cause health problems.
  • Therefore, during large public gatherings like Pandharpur vari mobile toilets like Ecosan are deployed by the government.

(5) How Indian culture and traditions helped in bio-diversity conservation? Give importance of conservation in terms of utilitarian reasons.

Answer :

(a) Indian culture and traditions helped in bio-diversity conservation :

  • Indian culture and traditions promote biodiversity conservation through various festivals and practices.
  • Nagpanchami festival honors snakes, highlighting the importance of respecting snakes and rat populations in the ecosystem, while Vatapoumima festival honors banyan trees.
  • Other festivals teach the value of plants and animals, and even cattle are worshipped as a tradition.
  • Jain religion strongly advocates for animal protection through vegetarianism,

(b) Importance of conservation in terms of utilitarian reasons :

The conservation of biodiversity can be done in utilitarian way or for ethical reasons.

Utilitarian reasons are further classified into narrowly utilitarian and broadly utilitarian reasons.

Narrowly utilitarian reasons :

  • Biodiversity provides material benefits to humans, including resources for basic needs like food, clothing, and shelter.
  • It also contributes to industrial products like resins, tannins, and perfume base. However, it is often sacrificed for aesthetic purposes like ornaments or artefacts.
  • Biodiversity also contributes to medicines, which account for 25% of the global medicine market. Around 25,000 species are used for traditional medicines by tribal populations worldwide.
  • Bioprospecting is the systematic search for new sources of chemical substances and genes. Microorganisms, macroorganisms, and other significant natural products, including commercially important species, are also due to biodiversity.

Broadly utilitarian reasons :

  • Green plants' oxygen production aids human survival. Amazon forest provides 25% of global oxygen.
  • Insects' role in pollination and seed dispersal is crucial for crop and fruit production.
  • Biodiversity aids in human recreation.
  • Conservation of biodiversity is essential considering these utilitarian reasons.

Therefore, to protect and conserve our rich biodiversity on the planet, we have to remember all the utilitarian reasons.

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