RBSE Solutions Class 12 Biology Chapter 19 Sustainable Agriculture

RBSE Class 12 Biology Chapter 19 Multiple Choice Questions

Question 1. Alga used as bio fertiliser is?
(a) Cladophora
(b) Nostoc
(c) Spirogyra
(d) All of the options
Answer: (b) Nostoc
In simple words: Nostoc is a type of blue-green alga that is commonly used as a natural fertilizer in farming because it helps fix nitrogen in the soil.

🎯 Exam Tip: Remember specific examples of bio-fertilizers. Blue-green algae like Nostoc are important for their nitrogen-fixing abilities, especially in rice fields.

Question 2. Root nodules of leguminous plants contain which bacterium -
(a) Anabaena
(b) Cyanobacteria
(c) Rhizobium
Answer: (c) Rhizobium
In simple words: Leguminous plants, like peas and beans, have special bumps on their roots called nodules. Inside these nodules live tiny bacteria called Rhizobium, which help the plant get nitrogen from the air.

🎯 Exam Tip: Know the symbiotic relationship between Rhizobium bacteria and leguminous plants, as it is a classic example of natural nitrogen fixation.

Question 3. Heterocyst is connected to which of the following?
(a) Virus
(b) Bacteria
(c) Nostoc
(d) Rhizobium
Answer: (c) Nostoc
In simple words: Heterocysts are specialized cells found in some cyanobacteria, like Nostoc, which are responsible for changing atmospheric nitrogen into a form plants can use.

🎯 Exam Tip: Understand the role of heterocysts in nitrogen fixation and their association with specific cyanobacteria like Nostoc or Anabaena.

Question 4. Which free-living bacterium fix atmospheric nitrogen -
(a) Rhizobium
(b) E.coli
(c) Azotobactor
(d) All of the options
Answer: (c) Azotobactor
In simple words: Azotobacter is a bacterium that lives freely in the soil and can take nitrogen directly from the air, turning it into a nutrient for plants.

🎯 Exam Tip: Distinguish between symbiotic nitrogen-fixers (like Rhizobium) and free-living ones (like Azotobacter) and be able to give examples of each.

Question 5. Which of the following is not an example of sustainable agriculture.
(a) Mixed farming
(b) Condensed (Compact) agriculture
(c) Crop rotation
(d) Organic agriculture
Answer: (b) Condensed (Compact) agriculture
In simple words: Sustainable agriculture means farming in a way that protects the environment and resources for the future. Condensed or compact agriculture, which might involve very intense use of space or resources, is not typically seen as sustainable.

🎯 Exam Tip: Familiarize yourself with the principles and examples of sustainable agriculture practices, such as crop rotation and organic farming.

Question 6. Those biological factors which are used to kill insects weeds and pests are called -
(a) Biopesticides
(b) Chemical fertilizer
Answer: (a) Biopesticides
In simple words: Biopesticides are natural ways to control pests, using things like helpful bacteria, fungi, or extracts from plants instead of harmful chemical sprays.

🎯 Exam Tip: Understand the difference between biopesticides and chemical pesticides, highlighting the environmental benefits of the former.

RBSE Class 12 Biology Chapter 19 Very Short Answer Questions

Question 1. For the increase in production: 1. ....... 2. ........ are used.
Answer:
1. Chemical fertilizer
2. Pesticides
In simple words: To grow more crops, farmers often use chemical fertilizers to feed the plants and pesticides to kill harmful insects and weeds.

🎯 Exam Tip: When answering fill-in-the-blank questions, ensure your answers fit grammatically and contextually within the sentence.

Question 2. ........ is a natural way of doing farming.
Answer: Organic farming
In simple words: Organic farming is a way of growing food naturally, without using man-made chemicals or pesticides.

🎯 Exam Tip: Define organic farming clearly and its core principle of using natural methods.

Question 3. Microorganisms used to increase the fertility of soil are called ......
Answer: Biofertilizers.
In simple words: Tiny living things like bacteria and fungi, when used to make soil healthier and richer for plants, are called biofertilizers.

🎯 Exam Tip: The key term here is "biofertilizers" and recognizing their role in improving soil health through microbial activity.

Question 4. Name one phosphate dissolving bacterium.
Answer: Pseudomonas.
In simple words: Pseudomonas is a type of bacteria that can help plants by breaking down phosphates in the soil, making them easier for plants to absorb.

🎯 Exam Tip: Remember specific examples of beneficial microorganisms and their functions in agriculture.

Question 5. Those animals or plants or microbes which destroy crops and their products are known as?
Answer: Pests (e.g., Bacillus thuringiensis can be used against them).
In simple words: Any living thing, big or small, that harms our crops or food after it's harvested is called a pest.

🎯 Exam Tip: A clear definition of "pests" is important, along with understanding that they include various types of organisms.

Question 7. Which research institute is doing research on Anabaenaazollae.
Answer: Central Rice Research Institute, Cuttack
In simple words: The Central Rice Research Institute in Cuttack studies Anabaenaazollae because it helps rice plants grow better.

🎯 Exam Tip: Specific institutions are often associated with particular agricultural research areas. Knowing them shows good general knowledge.

Question 8. Give some examples of non-symbiotic bacteria which fixe atmospheric nitrogen.
Answer: Azotobactor, Azospirilum
In simple words: Azotobacter and Azospirillum are bacteria that live freely in the soil and can take nitrogen from the air to make it useful for plants.

🎯 Exam Tip: Be able to name at least two examples of free-living, non-symbiotic nitrogen-fixing bacteria.

RBSE Class 12 Biology Chapter 19 Short Answer Questions

Question 1. What do you understand by Sustainable Agriculture?
Answer: Sustainable agriculture is an approach to farming that involves a mix of practices for growing crops and raising animals. The main goal is to keep the farming land productive and healthy for a long time without causing any harm to the environment. This way, it can meet people's food needs for many years.
In simple words: Sustainable agriculture is farming in a smart way that keeps the land healthy, protects nature, and makes sure we can grow food for everyone now and in the future.

🎯 Exam Tip: Define sustainable agriculture by focusing on its long-term benefits for both the environment and human needs.

Question 2. Why need of sustainable agriculture was realised? Explain.
Answer: In older times, people met their basic needs like food, clothes, and homes using plants. But over time, as the human population grew, their needs increased a lot. Things like population growth, new factories, and better transport put huge pressure on natural resources. Many of these resources are now running out quickly. If this continues, future generations will suffer because there won't be enough clean air, clean water, or nutritious food. Because of this worry, we started thinking globally about how to meet our current needs without harming the balance of nature. This is why sustainable agriculture became important.
In simple words: We realized we needed sustainable agriculture because more people and factories were using up Earth's natural resources too fast, making us worry there wouldn't be enough for the future.

🎯 Exam Tip: Explain the reasons for the shift towards sustainable agriculture, focusing on population growth, resource depletion, and environmental impact.

Question 1. Write an essay on Biofertilizers.
Answer:
Biofertilizers:
Modern scientists are growing microbes that can take nitrogen from the air on a large scale. These microbes make the soil rich in nutrients through their natural activities and are called biofertilizers. Biofertilizers also speed up the process of mineralization, which further improves soil fertility. Some examples of biofertilizers include Bacteria, Cyanobacteria, and Fungi.

These biofertilizers are mainly of six types:
1. Symbiotic bacterium – Rhizobium:
These bacteria live in the root bumps (nodules) of plants like peas and beans, getting food from the plant. They catch nitrogen from the air and turn it into ammonia, which is then released into the soil and used by the plant. Rhizobium can add 50 to 150 kg of nitrogen per hectare each year. Using these bacteria as biofertilizers can increase crop production by 15-20%. Even the next crop grown after their use will yield more due to improved soil fertility.

2. Non-symbiotic Bacteria:
Bacteria like Azotobacter, Azospirillum, and Clostridium can also fix nitrogen directly in the soil, making it available to plants. These bacteria absorb free nitrogen from the soil and change it into organic nitrogen compounds. When these bacteria die, other decomposing bacteria break down the nitrogen compounds, releasing ammonia. This ammonia then changes into nitrite and finally into nitrate, which plants can use. Azotobacter is used as a biofertilizer in growing rice, maize, and cotton, increasing production by up to 20%.

3. Blue-Green Algae or Cyanobacteria:
These increase rice production. Today, an aquatic plant called Azolla is also used with blue-green algae as an algal biofertilizer in Southern and South-East Asia. Azolla is a floating fern whose leaves contain blue-green algae like Anabaena Azolla, which fixes nitrogen. Anabaena pinata is also a good biofertilizer. When used with Azolla, it can boost rice production by 50%. Anabaena Azolla is mass-produced at the Central Rice Research Institute, Cuttack.

4. Mycorrhiza:
Mycorrhiza is a close relationship between fungi and the roots of higher plants. The fungus takes nutrients from the soil and gives them to the host plant, and in return, the host plant provides food to the fungus.

5. Phosphate dissolving Bacteria:
Some bacteria, like Pseudomonas, Microbacterium, and Bacillus, convert unavailable inorganic phosphate into a form of organic phosphate that plants can easily absorb.

6. Organic manure:
In India, a lot of organic waste products are available, such as household waste, city waste, sewage, crop leftovers, animal poop, and bone powder. These wastes can be turned into organic manure through microbial breakdown and then used by plants.
In simple words: Biofertilizers are natural microbes that enrich soil with nutrients, helping plants grow better. They include different types of bacteria, algae, and fungi that fix nitrogen or make other nutrients available, reducing the need for chemical fertilizers.

🎯 Exam Tip: When writing an essay on biofertilizers, include a clear definition, explain their importance, and provide specific examples for each type (symbiotic, non-symbiotic, algae, mycorrhiza, phosphate-dissolving, and organic manure).

Question 4. Write two advantages of Blue-green algae in farming.
Answer:
• Blue-green algae (Cyanobacteria), such as Anabaena, Nostoc, and Plectonema, along with other non-symbiotic bacteria, help in fixing nitrogen from the air. Blue-green algae have a special cell called a Heterocyst, which is where the nif gene helps with nitrogen fixation.
• Rice fields are perfect for blue-green algae to grow. Using blue-green algae in paddy fields helps increase crop production.
In simple words: Blue-green algae are good for farming because they add nitrogen to the soil and boost crop production, especially in rice fields.

🎯 Exam Tip: Focus on the key benefits: nitrogen fixation and increased yield, especially in waterlogged conditions like paddy fields.

Question 5. What are Biopesticides?
Answer: Pests are microbes, plants, and animals that harm crops or farm products. Viruses, bacteria, fungi, insects, or even large animals can be pests. Biopesticides are biological agents used to kill insects, weeds, and disease-causing organisms. Some viruses, bacteria, fungi, and protozoa are used as biopesticides.
In simple words: Biopesticides are natural ways to fight pests, using living things like certain viruses, bacteria, or fungi instead of chemical sprays to protect crops.

🎯 Exam Tip: Ensure your definition of biopesticides includes the types of organisms used and their purpose in pest control.

Question 6. How Bacillus thermogenesis is used as a biopesticide.
Answer: Bacillus thuringiensis is a bacterium that lives in the soil. It is Gram-positive, and its spores are known to be effective against certain pests.
In simple words: Bacillus thuringiensis (Bt) is a soil bacterium that creates substances which kill specific harmful insects, making it a natural pest control.

🎯 Exam Tip: Remember Bacillus thuringiensis (Bt) as a prime example of a bacterial biopesticide and its mechanism of action against insects.

Question 2. Explain biofarming/Organic agriculture.
Answer:
Aims of Organic Agriculture:
• To make the soil richer and keep it fertile for a long time.
• It helps increase the activity of microbes, soil organisms, plants, and other living things involved in farming.
• To use nature's systems in an eco-friendly way.
• It encourages using local farming methods and other types of energy in agriculture.
• To produce more food with high nutritional value.
• It stops pollution by using new farming technologies.
In simple words: Organic agriculture aims to keep soil healthy and productive naturally, boost biodiversity, use eco-friendly practices, and produce nutritious food without pollution, all while using local resources.

🎯 Exam Tip: List the primary goals of organic agriculture, emphasizing soil health, environmental protection, and food quality.

Question 4. What is mycorrhiza? Explain its importance.
Answer: Mycorrhiza is a close partnership between fungi and the roots of higher plants. The fungus helps the plant get nutrients from the soil, and in return, the plant provides food to the fungus.
In simple words: Mycorrhiza is a helpful team-up between a fungus and plant roots; the fungus brings nutrients to the plant, and the plant gives food to the fungus.

🎯 Exam Tip: Define mycorrhiza as a symbiotic relationship and highlight its benefit in nutrient absorption for plants.

Question 5. Explain the economic and ecological importance of organic agriculture/organic farming?
Answer:
Economic & Ecological Importance of Organic Agriculture:
• It is a simple and inexpensive method, so even small farmers can use it.
• Using biofertilizers makes the soil hold more water and allows more air in.
• The temperature and pH of the soil are maintained with biofertilizers, ensuring soil bacteria remain active.
• Organic farming reduces soil toxicity and helps maintain ecological balance.
• Biofertilizers can turn dry, infertile land into rich, fertile land. When biofertilizers break down, they produce organic acids that reduce soil alkalinity.
• It is environmentally friendly and keeps the soil healthy.
• Organic agriculture helps prevent soil erosion.
In simple words: Organic farming is good because it is cheap for farmers, makes soil healthier by improving water retention and aeration, balances the ecosystem, and prevents pollution and soil erosion, leading to fertile land.

🎯 Exam Tip: When discussing the importance of organic agriculture, make sure to cover both its economic advantages (cost-effective, turns barren land fertile) and ecological benefits (soil health, pollution prevention, ecological balance).

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