NCERT Solutions Class 12 Biology Chapter 16

Biology is a popular discipline that deals with the study of living things. Biology students use scientific procedures to understand the diversity of life and the interrelationships between organisms and their surroundings. In addition, they learn how to use live creatures and their products to improve human health and the environment. The Greek words “bios,” which means “life,” and “logos,” which means “knowledge” or “learning,” are combined to form the word biology.

The 16th Chapter of Class 12 Biology is Environmental Issues. Questions about the causes of environmental imbalances, risks to natural resources because of environmental inequalities, and so on will be found in this Chapter. Environmental Issues are the negative consequences of human activity on the environment. For example, it degrades the quality of the air, water, and soil. These unfavourable circumstances result in environmental difficulties that impact the environment’s natural condition.

Biology comes under the list of one of the students’ favourite subjects. But unfortunately, most students have trouble remembering key terminology and frequently fail to understand essential life processes. Extramarks has developed Biology Class 12 Chapter 16 NCERT Solutions to overcome this fear. The subject experts having years of experience have developed these solutions so that students can take help from solved chapter end questions .

Apart from these, Extramarks offers students a variety of study materials to choose from.. Material such as NCERT exemplar, CBSE revision notes, CBSE sample papers, CBSE past years’ question papers, and more are waiting for them at the Extramarks’ website.

Key Topics Covered in NCERT Solutions Class 12 Biology Chapter 16

 The key topics  covered in NCERT Solutions Class 12 Biology Chapter 16- Environmental Issues are mentioned below:

Let us now look at Extramarks’ in-depth information on each subtopic in NCERT Solutions Class 12 Biology Chapter 16- Environmental Issues.

Air Pollution and its Control

NCERT Solutions Class 12 Biology Chapter 16 explains the concept of Air pollution and its control in the following section. Both plants and animals are harmed by air pollution. Crop development and production are harmed by air pollution. In addition, humans’ respiratory systems are affected. Thermal power plants, smelters, and other industries emit particulate and gaseous air pollutants. These contaminants are hazardous and should be filtered before being discharged into the environment. An electrostatic precipitator is the most extensively used technology for removing particulate particles. Inhaling particulate matter causes breathing and respiratory difficulties, inflammations, irritations, and even premature mortality.

Excessive usage of automobiles is another major source of air pollution in urban areas. Catalytic converters, which use precious metals such as platinum, palladium, and rhodium as catalysts, are installed in cars to avoid the emission of hazardous gases. Toxic emissions can be reduced by using unleaded gasoline or diesel. In 1981, the Air (Prevention and Control of Pollution) Act became law. In India, the Air Act was enacted in 1981 to address pollution prevention and control. The Air Act was revised in 1987 to add noise as an air contaminant.

Controlling Vehicular Air Pollution: A Case Study of Delhi

Delhi, India’s capital, leads the country in its level of air pollution. The problem of Delhi’s air pollution became so bad that public interest litigation (PIL) was filed in India’s Supreme Court. As a result, the Supreme Court strongly asked the government to take necessary measures including switching public vehicles from diesel to compressed natural gas (CNG). CNG is favoured because it is inexpensive, burns efficiently, and very little of it is left unburnt Other techniques for reducing pollution in Delhi included the use of unleaded gasoline, the phase-out of outdated automobiles, and use of low-sulfur petrol or diesel , etc. 

Water Pollution and its Control

NCERT Solutions Class 12 Biology Chapter 16 explains that the government passed the Water (Prevention and Control of Pollution) Act of 1974 in response to rising water pollution to protect our water resources.

Domestic Sewage and Industrial Effluents

Domestic sewage is not safe for human consumption even if it contains 0.1 per cent contaminants. Solids are simple to remove, while dissolved salts like nitrates, phosphates, and other nutrients are more challenging. Domestic sewage primarily comprises biodegradable organic materials that microbes may degrade. Biological oxygen demand can measure the quantity of biodegradable organic matter in sewage water. High nutrients cause excessive development of planktonic (free-floating) algae in water bodies. This is known as an algal bloom, which gives the water bodies a characteristic hue.

Sources of Water Pollution

NCERT Solutions Class 12 Biology Chapter 16 states that water contamination is caused by two factors which are as follows:

• The sources that come from a single, identified source are referred to as point sources. For example, consider a pipe or a ditch.
• Non-point sources result from diffuse pollutants originating from several points or sources. Nutrient run-off from agricultural land, for example.

Effects of Water Pollution

• Depletion of oxygen can cause aquatic creatures to die.
• Ecosystem imbalance.
• Various illnesses are caused by contaminated water. Cholera, dysentery, diarrhoea, TB, jaundice, and other fatal diseases are caused by dirty water. Bacteria cause approximately 80% of stomach disorders. Polluted water is the reason for electronic water repellents in India.

Integrated wastewater treatment: A Case Study

For wastewater treatment, both artificial and natural techniques are utilised. It involves:

• Sedimentation in the traditional sense, followed by filtering and chlorine treatment.
• Following the completion of the first stage, the scientists created a network of six interconnected wetlands spanning 60 hectares of marshland. Suitable plants, algae, fungus, and bacteria were sown in these marshes. They absorb, neutralise, and digest contaminants. The water is organically cleansed as it passes through the swamps in this way.

Solid Wastes

NCERT Solutions Class 12 Biology Chapter 16 explains the concept of Solid waste and a case study.

Municipal solid wastes are waste from offices, schools, retailers, and hospitals. Flies and rodents are attracted to the disposal of these wastes. Sanitary landfills are made out of depressions or trenches into which trash is deposited. Biodegradable, non-biodegradable, and recyclable waste are the three types of waste. Biodegradable wastes can be buried in the ground and will break down into harmless by-products. Non-biodegradable wastes cannot decompose spontaneously. As a result, their usage must be limited. Wastes that can be recycled can be used to recover at least a few usable materials. Non-biodegradable trash should be recycled to the greatest extent practicable. Hospital waste is hazardous. To avoid contamination and the spread of germs and toxic chemicals, they must be burnt appropriately.

Case Study of Remedy for Plastic Waste

Ahmed Khan, a plastic bag producer in Bangalore, came up with a solution to the ever-increasing plastic trash. Polyblend emerged as the solution. Polyblend is a fine powder derived from plastic trash that has been reprocessed. They’re frequently combined with bitumen and used in road construction. This boosts the bitumen’s water repellent characteristics, extending the road’s lifespan.

Agro-chemicals and their effects

For agricultural production, the usage of fertilisers and insecticides has expanded dramatically. However, overuse of chemical fertilisers hurts soil fertility and crop output. In addition, they have the potential to pollute the land, water, and air.

Case Study of Organic Farming

Integrated organic farming is an environmentally beneficial, circular process that produces no waste. Instead, waste products from one operation are cycled and utilised as nutrients for other functions. This provides for the most efficient use of resources and boosts production efficiency. Crop waste may also be utilised as a natural fertiliser in the composting process.

Radioactive Wastes

NCERT Solutions Class 12 Biology Chapter 16 also discusses another important topic of Radioactive Waste.

The radiation released by nuclear waste is exceedingly dangerous. Because it induces mutations, it impacts both plants and animals. In addition, nuclear radiation is harmful in large amounts and causes various illnesses at lower doses, ]most oftenly cancer. As a result, nuclear waste is a hazardous contaminant that must be handled with extreme caution.

Greenhouse Effect and Global Warming

The sun’s rays reach the earth’s surface and warm up the atmosphere. The earth’s atmosphere traps the sun’s rays, raising the earth’s temperature. The greenhouse effect is what causes this. Greenhouse gases include carbon dioxide, methane, acid, and water vapour. When the concentration of these gases rises, it traps more sunlight leading to  rise in the earth’s temperature. This is popularly known as Global warming. Climate change will influence food production and agriculture as temperatures rise, causing glacier melting, weather fluctuations, and oxygen depletion.

Ozone Depletion in the Stratosphere

Ozone depletion is another crucial topic discussed in NCERT Solutions Class 12 Biology Chapter 16. The stratosphere contains ozone, which shields the atmosphere from damaging UV light. Ultraviolet rays are highly destructive to living things. They are toxic to DNA and proteins found in living things. The dobson unit is known to measure the thickness of the ozone layer in a column of air from the soil to the top of the atmosphere. When oxygen absorbs UV light, it splits into oxygen atoms. When oxygen atoms mix with oxygen, ozone is created. A category of compounds known as chlorofluorocarbons (CFCs), such as Freon, is the primary cause of ozone depletion. Refrigerators contain CFCs. These CFCs absorb UV light and produce chlorine free radicals in the atmosphere.

Degradation by Improper Resource Utilisation and Maintenance

NCERT Solutions Class 12 Biology Chapter 16 explains degradation of natural resources due to improper resource usage in this section.

Soil Erosion and Desertification

It takes millennia for fertile topsoil to develop. However, human activities such as overgrazing, over-cultivation,  deforestation, and improper irrigation techniques cause soil erosion. This causes topsoil loss and the creation of arid terrain. Increased development will eventually lead to desertification and is a severe danger to soil integrity.

Waterlogging and Soil Salinity

Waterlogging occurs when water is not adequately drained. The accumulation of water also influences the attraction and dissolution of water-soluble salts. Subsequently, these salts are deposited as a thin crust on the soil surface or gathered around plant roots. An increase in soil salinity impacts plant development and can also harm agriculture. Increased waterlogging and soil salinity have arisen during the green revolution.

Deforestation

NCERT Solutions Class 12 Biology Chapter 16 explains that deforestation is the gradual disappearance of forest and tree cover due to careless tree felling. Therefore, it is caused by human activities.

Causes of Deforestation

• Conversion of forests to farmlands

Trees are chopped down, and stumps are burned to clean the forest. The ash is utilised as fertiliser, and the land is used for farming. The land is kept fallow after agricultural production to enable the soil nutrients to recover. Because of the rapid rise in population, grounds do not have enough time to recuperate and produce forests.

• Urbanisation 

Rapid urbanisation has resulted in uncontrolled forest removal for many objectives, including agriculture, housing, industries, etc.

NCERT Solutions Class 12 Biology Chapter 16 Exercise and Solutions

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Class 12 Biology Chapter 16: Very Short Answer Type Questions

Class 12 Biology Chapter 16: Short Answer Type Questions

Class 12 Biology Chapter 16: Long Answer Type Questions

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Key Features of NCERT Solutions Class 12 Biology Chapter 16

Students are frequently advised to go through NCERT questions when studying for exams. These NCERT questions are an excellent combination of all the concepts in the chapter. Extramarks’ NCERT Solutions are meant to help students understand every question in any tricky chapter. Here are some of the benefits of using Extramarks:

• They cover all the solutions to the chapter related questions in the NCERT textbook as well as additional important questions 
• These solutions help students clarify their doubts and practise the exam writing pattern appropriately.
•  Through regular practice, students will be able to increase their understanding of the chapter and build a strong foundation on the concepts. 
• The answers in NCERT solutions are explained in detail, which gives students an idea of how to attempt a question in the board exam in the right manner. ·       
•  A team of subject matter experts has prepared the study material while ensuring that it is highly accurate and easy to understand.