Maharashtra Board Class 12 Solutions for Biology Chapter 15 Biodiversity, Conservation And Environmental Issues - PDF

Choose The Correct Option

1. Observe the graph and select the correct option. 

Species Richness

1. Line A represents, S = CA²

2. Line B represents, log C = log A + Z log S

3. Line A represents, S = CA^Z

4. Line B represents, log S = log Z + C log A

Ans: The correct option is (c) Line A represents, S = CA^Z.

The graph shows the relationship between the species and the area. Alexander Von Humboldt studied this relationship and concluded that species richness increases with the area but up to some limit. The slope of the line is indicated by Z. When large areas are studied, the slope of line A becomes steeper.  

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

1. Zoological park 

2. Tissue culture 

3. Sacred grooves 

4. Cryopreservation

Ans: The correct option is (c) Sacred grooves. 

There are two types of species conservation on the basis of their conservation habitats. These are: in situ conservation and ex situ conservation. When species are conserved in their actual or natural habitats then it is called in situ conservation. Examples are national parks, sacred grooves, wildlife sanctuaries etc. On the other hand, ex-situ conservation includes the conservation of species outside their natural habitats and in man-made conditions that are similar to the natural habitat of species. Examples are zoological parks, cryopreservation, tissue culture etc. 

3. Which of the following factors will favour species diversity?

1. Invasive species

2. Glaciation

3. Forest canopy

4. Co extinction 

Ans: The correct option is (c) Forest canopy.

Species diversity means the different variety of species found in an area. The Forest canopy favours species diversity as it allows the growth of shade-loving plants called sciophytes. The different varieties of plants grow together. On the other hand, invasive species, glaciation and co-extinction decrease species richness in an area.

4. The term “terror of Bengal” is used for _______________.

• Algal bloom 

• Water hyacinth 

• Increased BOD

• Eutrophication

Ans: The correct option is (b) Water hyacinth.

Also known as Eichhornia crassipes, the water hyacinth is an invasive species outside its native region 'Amazon'. The plant was brought to Bengal because of its attractive flowers and leaves. As the plant reproduces by stolons and produces thousands of seeds in one year with a 28 years viable period, the plant became invasive in Bengal. Water hyacinth plants drained oxygen from aquatic bodies which killed many fishes inhabiting there. Fishes are an important food in the Bengal region but due to this invasive species, the scarcity of fish occurred in this state. Hence, water hyacinth is known as the "terror of Bengal". 

5. CFC are air polluting agents which are produced by ________________. 

1. Diesel trucks 

2. Jet planes

3. Rice fields

4. Industries

Ans: The correct option is (b) Jet planes.

Chlorofluorocarbons (CFCs) are chemicals that are used in refrigerators and air conditioners as refrigerants. Besides this, these chemicals are also used as air propellants and aerosols in jet planes. These chemicals enter the ozone layer and along with oxides of nitrogen are responsible for the depletion of the ozone layer. Methane gas is released from the rice fields. Carbon dioxide, nitrogen, and carbon monoxide gas are released from vehicles.  

Very Short Answer Type Questions

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

Ans: Two biodegradable materials that are released from the sugar industry are molasses and bagasse. These substances do not cause pollution as they can be easily broken down into smaller substances by soil microorganisms. There are two types of substances based on whether they can be degraded naturally or not. These are biodegradable and non-biodegradable substances. Biodegradable substances are easily degraded by soil microorganisms while non-biodegradable substances cannot be degraded by microorganisms. 

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

Ans: Two modern techniques of protection of endangered species are: 

• Tissue Culture: It is a modern method to conserve species that are threatened or facing extinction. The tissue culture method involves the propagation of plant species on a wide scale. This method is also used to conserve seeds of endangered species that produce few seeds. 

• Cryopreservation: It is a storage method to conserve those species that are cold tolerant. This method preserves the gametes of endangered species for a long time in cold storage. The gametes remain viable and fertile. 

3. Where was the ozone hole discovered?

Ans: In 1985, the first ozone hole was discovered in Antarctica by British scientists. They found the thinning of the ozone layer in the Antarctic region above the Halley research station and named it the ozone hole. The Ozone layer in the stratosphere protects living organisms from the harmful UV radiations of the sun. If the ozone layer gets depleted then the UV radiation will enter the troposphere and affect human health. Several problems such as the burning of the skin, skin cancer, and cataracts are caused due to exposure to UV radiation. 

4. Give one example of natural pollutants. 

Ans: An example of a natural pollutant is volcanic ash. There are two types of pollutants based on their source. These are natural sources and anthropogenic sources. The pollutants that are released from natural sources are called natural pollutants. Some examples of natural pollutants are dust, fog and volcanic eruption. The pollutants that are released from human-made sources are called anthropogenic or human-made pollutants. Some examples of anthropogenic pollutants are vehicle exhaust, combustion of fossil fuels, and CFCs. 

5. What do you understand about the EW category of living beings? 

Ans: EW means extinct in the wild. According to IUCN, it is a category that includes the individuals of a species that have become extinct in the wild due to the great loss of their habitats. These members of a species are not found in their original geographical areas. These organisms are found in captivity and cultivated under human care to save them from getting extinct. Hawaiian crow and Guam kingfisher are some examples of organisms that are extinct in the wild. 

Short Answer Type Qestions

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

Ans: Dandiya raas is not allowed after 10.00 pm. because it involves the use of loudspeakers and amplifiers that cause sleeplessness, increased heart beat etc. 

• The addition of increased noise in the environment causes several impacts on human health. 

• It causes insomnia, anger, stress, behavioural problems etc. There is a need to make people aware of the harmful effects of noise pollution. 

• Hence, the Supreme Court of India has prohibited the use of loudspeakers, firecrackers and amplifiers in social gatherings such as festivals and parties after 10 pm. 

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

Ans: The species richness of an area is determined by two main factors: temperature and rainfall. High temperatures and good rainfall favour the growth of plants and animals. As tropical regions receive a high amount of rainfall and high temperature, hence, these regions are rich in species and biodiversity. On the other hand, in colder regions such as the poles, the temperature and rainfall are very low, which does not support the growth of huge vegetation and wildlife. The polar areas are characterised by fewer species. 

3. How does genetic diversity affect sustenance of a species? 

Ans: Genetic diversity means the presence of different types of genes in a population. 

• Genetic diversity promotes the sustenance of species by making the species capable of adapting to changing environmental conditions. 

• Large genetic diversity supports the evolution process. 

• The presence of different alleles for disease resistance favours the good health of individuals of a species and thus, they will reproduce more. 

4. Greenhouse effect is boon or bane? Give your opinion. 

Ans: The greenhouse effect is a boon for us because without the greenhouse effect our earth would have a temperature of -18°C. The greenhouse effect is responsible for the trapping of solar radiation to the surface of the Earth. This makes the earth's atmosphere warm. Without the greenhouse effect, our earth would be a cold planet. The gases that are responsible for the trapping of sunlight are called greenhouse gases. Some greenhouse gases are carbon monoxide, water vapours etc. However, increased human activities such as industrialisation and deforestation have led to the increased concentration of greenhouse gases in the atmosphere. This further increases the earth's temperature which leads to global warming. Hence, the natural greenhouse effect is a boon for us but human enhanced greenhouse effect is a bane for us. 

5. How does CO cause dizziness and exhaustion?

Ans: Carbon monoxide is a toxic gas that causes harmful effects on the human body once inhaled. In enclosed areas, it causes severe effects on the body organs. This is because carbon monoxide gas binds more rapidly with the haemoglobin than oxygen to form carboxyhemoglobin. This makes the haemoglobin deficient for the binding of oxygen. Hence, an adequate amount of oxygen will not reach the different parts of the body including the brain. Thus, inhaling carbon monoxide gas will cause dizziness, headache, exhaustion, giddiness, cardiovascular disorders etc. In certain cases, inhaling carbon monoxide can be fatal.  

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

Ans: Two types of particulate pollutants found in the air are gaseous pollutants and particulate pollutants. 

• Gaseous pollutants are present in the air in the form of gases. These pollutant gases are carbon dioxide, carbon monoxide, oxides of nitrogen, sulphur dioxide etc. Gaseous air pollutants affect the environment and human health. They cause acid rain, the greenhouse effect, and global warming. In humans, gaseous air pollutants are responsible for lung and heart problems. They also affect the buildings, soil and wildlife. 

• Particulate air pollutants are present in the air as suspended particles. These particulate matters are heavy metals, smoke particles, dust, soot etc. These minute, solid particles enter our respiratory system and cause several respiratory diseases such as breathing problems, running nose emphysema, bronchitis etc. Other health problems due to particulate matter are irritation to the eyes, nose, headache etc. 

Long Answer Type Questions

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

Ans: Montreal protocol is an essential step because 

• Every country recognised that ozone depletion can lead to harmful UV radiation reaching the earth's surface. This causes a serious risk to people, animals and the environment. So, quick action was required to counteract this effect.

• The goal of all of these initiatives was to lower CFC and other ozone-depleting chemical emissions.

• This international treaty has helped in reducing the production and consumption of ozone-depleting substances. 

• The Montreal Protocol was a very wise decision because the ozone layer has been in much better condition since 1987.

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

Ans: Saalumara Thimmakka and Moirangthem Loinga are two environmental conservationists that play a very important role in controlling deforestation in our country. Their work is elaborated below: 

• Saalumara Thimmakka: She is a famous environmentalist from the Indian state of Karnataka who is credited with planting and caring for 385 banyan trees along a 45-kilometre section of roadway between Hulikal and Kudur. Also, she has planted around 8000 additional trees.

• Moirangthem Loinga: Moirangthem Loiya, a 45-year-old Manipur resident, stands out as a leading figure at a time when climate change and global warming are affecting all of us. He is responsible for restoring a forest called Punshilok, which means "Spring of Life." Punshilok is a living example of the excellent work he has done to preserve the environment and stop pollution.

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

Ans: BS emission standards are changed according to the norms set under the fuel policy released by the government. It depends on the traffic on the road and the changing environmental conditions.

BS emission standards are important to control air pollution by reducing the number of pollutants released from vehicles. BS standards aim to reduce the emission of some pollutants from vehicles. It also sets norms to maintain vehicle efficiency so that fewer pollutants are released. To maintain the quality of air, the BS standards are set by the government from time to time. 

4. During large public gatherings like Pandharpur Vari mobile toilets are deployed by the government. Explain how this organic waste is disposed of?

Ans: The mobile toilets that are deployed by the government in large public gatherings are an example of ecosan or ecological sanitation. This is an ecological and cost-effective way to dispose of human waste. The use of ecosan toilets saves water and prevents the production of sewage. Mobile toilets are dry composting toilets that contain a pit. When the pit is filled with human waste, it is closed by a lid. After 9-10 months, human waste is converted into organic manure that is used in agriculture. Thus, this type of toilet is used where water is scarce. Adding organic manure in agriculture reduces our dependence on chemical fertilisers. Hence, mobile toilets are a sustainable way to dispose of human excreta. 

5. How Indian culture and traditions helped in biodiversity conservation? Give importance to conservation in terms of utilitarian reasons. 

Ans: Indian culture and traditions helped in the conservation of biodiversity in the following ways: 

• The traditional people protect some trees and animal species in the name of God and they are part of their rituals. 

• Indian culture and traditions are related to nature and protect it. The tribal groups worship some sacred plants and animals and these are called sacred grooves. 

• The tribals do not allow the cutting and killing of trees and animals. 

• Some examples of sacred groves are in Maharashtra, Karnataka and the Garo, Khasi and Jaintia hills of Assam. 

The Importance of Conservation is:

• Trees are used to fulfil many basic human needs such as clothing, paper, food, wood etc. 

• The incredible medicinal value of herbs and trees is known to all of us. Many plants are also used today to treat various diseases. 

• The trees add oxygen to the environment. The Amazon forests of South America provide 20% of the total oxygen of the Earth. 

• Rich biodiversity promotes a balanced ecosystem by ensuring the pollination and dispersal of seeds. 

Importance of Maharashtra Board Class 12 Biology Chapter 15 Biodiversity Conservation and Environmental Issues

This chapter, as mentioned earlier, explains what biodiversity is and how its conservation is important. It explains the diversity we can see in living organisms with respect to shapes, colors, mode of nutrition, form, etc.

It will explain how the term evolved and what it means. The proper explanation will be given based on examples so that you can understand these concepts well. To make it easier, refer to the Maharashtra Board Class 12 Biology solutions Chapter 15 Biodiversity Conservation and Environmental Issues prepared by the subject experts. Learn what the environmental issues are and how the world is striving to tackle them.

There are different levels of diversity we find in an ecosystem. These diversities are the result of ages of evolution and adaptation to a particular environment. This chapter explains how Biodiversity Conservation and Environmental Issues are interrelated.

We can also observe various patterns in the biodiversity seen in different ecosystems. The diversification among the organisms can be seen increasing when we go closer to the Equator from the poles. To understand these fundamental principles, follow the solutions and check the examples given in this chapter.

Benefits of Biodiversity and Conservation Class 12 PDF Solutions

• This is a crucial chapter in the syllabus of Class 12 Biology. These solutions will help you understand the concepts. The simpler version of these concepts and principles will help you memorize them easily.

• You will also be able to comprehend the easier version of this chapter and revise using the solutions. These solutions will also simplify the relationship between the area and the species surviving there. Hence, your preparation will become faster and better.

• You can easily use these solutions to clarify doubts on your own and save your precious preparation time.

• Focus on preparing the chapter and start referring to the Biodiversity Conservation and Environmental Issues exercise answers. Find out how the experts have solved the questions and develop your answering skills. This is how you can score well in the board exams.

Download Biodiversity and Conservation Class 12 Solutions PDF

Get the free version of these solutions along with the exercise solutions for this chapter. Take a step ahead of the competition and focus on how to make your study sessions better. Utilize the simpler version of the concepts and scientific terms of this chapter to memorize and recall answers faster during an exam.