RBSE Solutions Class 12 Biology Chapter 20 Bioenergy

Rbse Class 12 Biology Chapter 20 Multiple Choice Questions

Question 1. Example of fossil fuel is?
(a) Alcohol
(b) Gobar Gas
(c) Petrol
(d) Hydrogen
Answer: (c) Petrol
In simple words: Fossil fuels are formed from the remains of ancient plants and animals. Petrol is a well-known example of a fossil fuel, essential for vehicles.

🎯 Exam Tip: Know the difference between renewable and non-renewable energy sources. Fossil fuels are non-renewable and take millions of years to form.

Question 2. Major component gas in Gobar gas is?
(a) CO3 and H2
(b) CH2 and H2
(c) CH4 and CO2
Answer: (c) CH4 and CO2
In simple words: Biogas, often called Gobar gas, mainly consists of methane (CH4) and carbon dioxide (CO2). Methane is the part that burns and provides energy.

🎯 Exam Tip: Remember the main gases in biogas; methane is crucial for its energy value, while carbon dioxide is also a significant component.

Question 3. Energy obtained from living organisms/biological factors is?
(a) Bioenergy
(b) Biofuel
(c) Mechanical Energy
(d) Biomass
Answer: (a) Bioenergy
In simple words: Energy that comes from living things or their waste is called bioenergy. It is a renewable source, meaning it can be naturally replenished.

🎯 Exam Tip: Understand the term "bioenergy" and distinguish it from "biofuel" (which is a type of bioenergy) and "biomass" (which is the material used to produce bioenergy).

Question 4. Presence of which gas makes biogas less effective in terms of natural gas?
(a) H2
(b) CH2
(c) CO2
(d) SO2
Answer: (c) CO2
In simple words: Carbon dioxide (CO2) does not burn and is present in biogas. This non-combustible gas lowers the overall energy value of biogas compared to natural gas, which has less CO2.

🎯 Exam Tip: A higher percentage of non-combustible gases like CO2 reduces the calorific value of fuel, making it less efficient for energy production.

Question 5. Which chemical component is added with petrol in automobiles/automotive?
(a) Ethanol
(b) Methanol
(c) Propanol
(d) Butanol
Answer: (a) Ethanol
In simple words: Ethanol is a type of alcohol that can be mixed with petrol for use in car engines. This blend is often called ethanol-blended petrol and helps reduce reliance on fossil fuels.

🎯 Exam Tip: Remember ethanol as a common biofuel additive for petrol, and know its role in reducing emissions and conserving fossil fuel resources.

Rbse Class 12 Biology Chapter 20 Very Short Answer Questions

Fill In The Blanks:

Question 1.
Answer:
1. Nonrenewable source of energy.
2. Bio-Energy
3. Bio-mass
4. Bio-gas or Gobar gas
5. 31
In simple words: These are the correct terms to complete the blanks for the given question.

🎯 Exam Tip: Pay attention to keywords when filling in blanks, especially those related to energy types, sources, and biological processes.

Question 2. Write the names of two petrol plants.
Answer:
• Euphorbia Lathyrus.
• Hevea brasiliensis.
In simple words: Two plants that produce substances similar to petrol are Euphorbia Lathyrus and Hevea brasiliensis, which can be processed into fuel.

🎯 Exam Tip: When asked for specific examples, ensure accurate spelling of scientific names and provide at least the requested number of examples.

Question 3. What is Petro farming?
Answer: Petro farming involves growing specific plants to produce biodiesel, which can replace diesel or petrol. These plants are often called Petro crops because their products are used as fuel. This practice helps to create alternative fuel sources.
In simple words: Petro farming is growing special plants to make fuel that can be used instead of diesel or petrol.

🎯 Exam Tip: Define key terms clearly and provide context for their importance, such as the purpose of Petro farming in fuel production.

Question 4. What is meant by energy crop?
Answer: Energy crops are plants specifically grown to be used as raw materials for making ethanol. Examples include sugarcane, sugarbeet, potato, maize, and turnip. Growing these plants is known as energy crop cultivation. These crops are an important source for producing biofuels.
In simple words: Energy crops are plants like sugarcane or maize grown to make ethanol fuel.

🎯 Exam Tip: Always provide relevant examples to support your definition when explaining biological or agricultural terms.

Rbse Class 12 Biology Chapter 20 Short Answer Questions

Question 1. What is Biodiesel?
Answer: Biodiesel is a renewable and environment-friendly fuel made from biological products like vegetable oils, fats, and latex. Chemically, it's known as fatty acid methyl ester (FAME). Rudolf Diesel, in 1895, laid the groundwork for the biodiesel concept by making an engine that could run on these oils. It's a clean-burning alternative to traditional diesel fuel.
In simple words: Biodiesel is an eco-friendly fuel made from plant oils and animal fats, used as a cleaner alternative to diesel.

🎯 Exam Tip: When defining a term like biodiesel, include its origin (biological products), chemical name (FAME), and its primary use as an alternative fuel.

Question 2. Write the importance of Biodiesel.
Answer: Biodiesel is important for several reasons:
• It works as a lubricant, which helps engines run more efficiently and lowers maintenance costs.
• Using biodiesel reduces harmful emissions like carbon monoxide and suspended particles from vehicle exhaust, making the air cleaner.
• It provides an alternative energy source, which can create jobs and increase income, especially in rural areas.
• Biodiesel can contribute to a country's economic stability and development, as the plants used to make it can be grown on infertile or non-irrigated land. This makes it a sustainable option for fuel production.
In simple words: Biodiesel helps engines, reduces pollution, creates jobs, and can be grown on poor land, making it important for the economy and environment.

🎯 Exam Tip: When discussing the importance of a fuel, consider its environmental impact, economic benefits, and operational advantages (like engine efficiency).

Question 3. What are the salient features of fuelwood?
Answer: Good fuelwood should have these important characteristics:
• It must burn easily and efficiently.
• It should have a high-calorie value, meaning it produces a lot of heat when burned.
• It should not break apart easily while burning.
• It needs to have low water and resin content so it can dry quickly and burn better.
• When it burns, it should produce less smoke and no unpleasant smell. Good quality fuelwood burns cleanly.
In simple words: Good fuelwood burns well, gives off a lot of heat, doesn't break easily, is dry, and produces little smoke or smell.

🎯 Exam Tip: Focus on the properties that make fuelwood efficient and desirable for use, such as its calorific value, burning characteristics, and low smoke production.

Question 4. Why the efficacy of Biogas is less than Natural gas.
Answer: Biogas is slightly less effective than natural gas because it contains about 31% carbon dioxide (CO2). Carbon dioxide does not burn, so its presence reduces the overall heating capacity of biogas. If the amount of CO2 in biogas could be reduced, its energy value would increase significantly.
In simple words: Biogas has less energy than natural gas because it contains carbon dioxide, which doesn't burn and lowers its heating power.

🎯 Exam Tip: When comparing fuel efficiencies, consider the composition of the gases, particularly the percentage of non-combustible components that dilute the fuel's calorific value.

Rbse Class 12 Biology Chapter 20 Essay Type Questions

Question 6. Give examples of Petro-plants.
Answer: Petro-plants are those whose products can be used as alternatives to fossil fuels like petrol and diesel. These plants belong to various families, including Apocynaceae, Asclepiadaceae, Euphorbiaceae, Sapotaceae, Urticaceae, and Compositae. Some specific examples of these plants are:
• Euphorbia Lathyrus.
• Calotropis prose.
• Plumeria sp.
• Ficus sp.
• Acharyas Zapata.
In simple words: Petro-plants are special plants like Euphorbia Lathyrus or Calotropis prose, whose parts can be turned into fuel instead of using petrol or diesel.

🎯 Exam Tip: When listing examples of plants, it is helpful to also mention the plant families they belong to, as this shows a broader understanding.

Question 7. What is Biomass?
Answer: Biomass is all the organic material created by photosynthesis in plants. Sunlight is the primary source of bioenergy, but only about 0.2% of the total solar energy reaching Earth is stored in plants as biomass. Since all living organisms rely on plants for their energy needs, either directly or indirectly, all living organisms and their by-products can be considered biomass, making it a potential energy source.
In simple words: Biomass is any living or once-living material, like plants or animal waste, that can be used as fuel. It's stored energy from the sun.

🎯 Exam Tip: Emphasize that biomass originates from photosynthesis, linking it directly to solar energy conversion and its broad definition encompassing all organic matter from living things.

Question 1. Explain in brief the examples of energy resources which are used against fossil fuel.
Answer: The main alternative energy resources to fossil fuels are:
1. Biomass: The sun is the primary source of bioenergy. Only 0.2% of the solar energy reaching Earth is stored in plants as biomass. All materials created through photosynthesis are called bio-mass. Since all living organisms depend on plants for their energy, all living organisms and their by-products can be used as biomass to generate energy.
Example: Wood, agricultural waste, and animal waste can all be used as biomass.
2. Firewood: Wood has been a common fuel for humans for a long time. About 50% of the Indian population uses wood fuel for home and small industries because it is readily available and easy to use. However, using wood as fuel, especially in many developing countries, significantly contributes to deforestation, wildlife destruction, and environmental pollution. Good fuelwood should have high burning potential, a good heating value, not break apart easily, have low moisture and resin, and produce little smoke or bad odor. Some plants that provide good quality fuelwood include:

3. Gobar gas or Biogas: Over 70% of India's population lives in villages where livestock is abundant. Cow dung, instead of being burned as cakes, should be used to make biofertilizer. This involves filling large pits regularly with dung. The organic compounds in the dung ferment due to bacteria, producing biogas. Gobar gas plants are widely used in India for energy and environmental pollution control. The anaerobic fermentation in Gobar gas plants happens in three stages:
• First, anaerobic bacteria break down complex organic materials like cellulose into simpler compounds.
• Second, bacteria convert these simpler compounds into carbonic acid, then into acetic acid.
• Third, Methanobacteria convert acetic acid into methane gas. The leftover material, called slurry, is dried and used as manure. Biogas is less effective than natural gas due to its 31% carbon dioxide content; reducing CO2 would increase its calorific value. Research is ongoing to improve the energy value of biowaste gases.
4. Biodiesel: Biodiesel is an eco-friendly, renewable fuel made from biological products like vegetable oils, fats, and latex, also known as fatty acid methyl ester (FAME). Plants convert solar energy into fats, sugar, or starch. Some plants also store hydrocarbons as storage oil in their seeds, which can be used as an energy source. This hydrocarbon forms the basis of the biodiesel concept, with Rudolf Diesel making an engine in 1895 that ran on these oils.
5. Algal hydrogen factory: Algae are aquatic plants that perform photosynthesis to produce carbohydrates and oxygen. In 2000, Anastasios Melis showed that if oxygen and sulfur supply to algae is stopped during the day, their metabolism changes, and they start producing hydrogen (H2) instead of oxygen. Since H2 is highly flammable, it could be a significant energy source. If these experiments succeed, algal hydrogen could become a major future energy source.
In simple words: Alternatives to fossil fuels include biomass (like wood and agricultural waste), firewood, biogas (from animal waste), biodiesel (from plant oils), and hydrogen from algae. Each offers ways to get energy from renewable sources instead of burning fossil fuels.

🎯 Exam Tip: For essay questions, structure your answer with clear headings or bullet points for each resource. Explain how each resource is produced and its advantages as an alternative to fossil fuels.

Question 2. Explain the process of formation of gobar gas.
Answer: Gobar gas, or biogas, is formed through the fermentation of organic compounds by bacteria. In India, cow dung is commonly used for biogas production. This process not only provides a cheap energy source but also helps control environmental pollution. The anaerobic fermentation in a Gobar gas plant happens in three main steps:
• In the first step, anaerobic bacteria break down complex organic substances like cellulose and hemicellulose into simpler compounds.
• In the second step, both partially aerobic and anaerobic bacteria convert these simpler components first into carbonic acid and then into acetic acid.
• In the third step, Methanobacteria convert the acetic acid into methane gas, which is the main combustible component of biogas. The remaining solid material in the biogas plant is called slurry, which is dried and used as manure. The effectiveness of biogas is slightly less than natural gas due to the presence of 31% carbon dioxide; reducing this CO2 percentage would increase its calorific value. Extensive research is ongoing to enhance the energy value of gases produced from biowaste fermentation.
In simple words: Gobar gas is made when bacteria break down organic waste like cow dung without air. This process happens in three steps: complex stuff breaks down, then becomes acid, and finally, methane gas is formed.

🎯 Exam Tip: Detail the three stages of anaerobic fermentation (breakdown, acid formation, methane production) and mention the key types of bacteria involved to score full marks.

Question 4. Write an essay on “How biodiesel can be an alternate source of energy as liquid fuel”.
Answer: Biodiesel offers a promising alternative liquid fuel source, particularly important for countries like India that rely heavily on imported petroleum products. Currently, India produces only about 30% of its petroleum needs, importing the remaining 70%. By blending just 5% biodiesel with diesel, India could significantly save foreign currency. Research suggests that oils from plants like Jatropha curcas can be effectively used to produce biodiesel.

The Planning Commission (now Niti Aayog) has proposed initiatives to cultivate Jatropha and Pongamia pinnata as part of a national biofuel mission. This cultivation is not only vital for biodiesel production but also helps bring uncultivated land into productive use. Such initiatives contribute positively to ecology and biodiversity conservation. Furthermore, they create employment opportunities and generate income for financially disadvantaged people and farmers, especially in rural areas.

Importance of Biodiesel:
1. Biodiesel acts as a lubricant, which enhances engine efficiency and reduces maintenance costs.
2. Its use leads to significantly lower emissions of carbon monoxide and suspended particles in vehicle exhaust, contributing to cleaner air.
3. Biodiesel serves as a crucial alternative energy source, fostering employment and increasing income.
4. Petro-plants, from which biodiesel is derived, can thrive in less productive, barren, non-irrigated, and roadside lands, making them economically viable.
• Biodiesel plays an important role in the efficient use of wasteland, promoting economic stability and national development.
• It is considered one of the best alternative fuels and can be produced by growing Petro-plants on unproductive lands.
• Cultivating Petro crops yields high-quality fuel while also protecting the environment, improving automobile efficiency, creating rural employment, and saving foreign exchange.
In simple words: Biodiesel is a great alternative fuel that helps countries save money on imports, reduces pollution, and creates jobs, especially because it comes from plants that can grow on less fertile land.

🎯 Exam Tip: In an essay, ensure a clear introduction to the problem (reliance on fossil fuels) and then detail how biodiesel addresses this, covering economic, environmental, and social benefits. Provide a strong conclusion that reiterates its potential.